nanosystems initiative munich€¦ · Jonathan Finley, Rudolf Gross and Gerhard Rempe Welcoming Message Dear ... Overview Overview Session 1 ..... 10 Session 2 ... Session 5 Session

NIM Conference on

Resonator QED

nanosystems initiative munich

Supported by

Munich 2017Aug 29 - Sep 1

Book of Abstracts

GeneralInformation

3RQED 2017

Welcome!Welcome

A very warm welcome to the NIM Conference on Resonator Quantum Electrodynamics RQED 2017 in Munich. The confer-ence is organized by the Cluster of Excellence “Nanosystems Initiative Munich” (NIM) which has been established by the Ger-man government’s “Excellence Initiative” in October 2006. The NIM Conference Series brings together leading international experts in quantum and nanosciences. It is aiming to provide a unique platform for the effective exchange of new scientific results and the open discussion of novel ideas.

The RQED 2017 Conference is a continuation of the highly successful RQED 2013 and 2015 Conferences, which also took place in Munich. It consists of tutorials (45 + 15 min) and invited talks (20 + 10 min), as well as a small number of contributed talks (15 + 5 min) addressing the follow-ing main topics: atomic cavity QED, solid state circuit and cav-ity QED, quantum information processing with cavity and circuit QED systems, cavity optomechanics and circuit nanoelectro-mechanics, low-dimensional QED systems, QED without cavity, hybrid quantum systems, nonlinear resonators, strongly inter-acting photons, Rydberg photonics, as well as propagating and entangled photons.

The RQED 2017 Conference aims to bridge different communi-ties in quantum physics – optical cavity QED, solid state cavity QED and solid state circuit QED – to share, pursue and diffuse

the benefits of collaborations in the science of elementary quan-ta. These fields made spectacular progress in the past years, with a striking diversity of demonstrated physical effects. It is remark-able that the circuit and cavity QED communities share the same physical concepts, whereas they explore different regimes with essentially different techniques. Such complementarities give a strong motivation to bring together the groups working in the different subfields to form a unified scientific community. Within RQED 2017, the Cluster of Excellence NIM intends to foster in-teractions between the leading international experts in the opti-cal cavity QED, solid state cavity QED and solid state circuit QED communities.

The organizing team is grateful to the excellence cluster NIM for generous financial support. We also acknowledge substan-tial support by the Walther-Meißner-Institute, the Max-Planck-Institute of Quantum Optics, the Walter Schottky Institute and JQI Maryland. Finally we are grateful to attocube systems AG and LOT-QuantumDesign GmbH for further sponsoring.

It is our great pleasure to welcome you to RQED 2017. We wish all participants a stimulating and fruitful meeting in a relaxed atmosphere.

Jonathan Finley, Rudolf Gross and Gerhard Rempe

Welcoming Message

Dear participants!

General GeneralInformation Information

4 5RQED 2017 RQED 2017

Content Map

U3, U6

Tram23

Content

Information ............... | 5

Talks ......................... | 8

Session 1 ........... | 10

Session 2 ........... | 15

Session 3 ........... | 21 Session 4 ........... | 26

Session 5 ........... | 32

Session 6 ........... | 37

Session 7 ........... | 44 Session 8 ........... | 49

Schedule (Center of Book) .. | 42

Poster Sessions ........ | 54

List of Participants .. | 80

The conferene takes place at the Kardinal-Wendel-Haus of the Katholische Akademie in Bayern (Mandlstraße 23, D-80802 München). It is situated next to the English Garden in Munich-Schwabing, an area famous for its bars and restaurants and very

popular among students and artists. At the same time the confer-ence site is a quiet and private place, since it is located inside the private park of Schloss Suresnes.

Conference Dinner

19:00, Thursday, August 31, 2017 Café Reitschule, Königinstraße 34

(5 minute walking distance from U-Bahn Station Giselastraße)

Kardinal Wendel Haus

Venue

Dinner

GeneralInformation

7RQED 2017

Lab ToursOverviewGeneralInformation

6 RQED 2017

Oral- & Poster Sessions

Oral Sessions include:

• Tutorials of 60 min (including 15 min of discussion) • Invited talks of 30 min (including 10 min of discussion) • Contributed talks of 20 min (including 5 min of discussion)

A projector with VGA connection is available in the lecture hall. Speakers can either bring their own laptop or a USB memory stick with their presentation. A laptop with a recent version of Mi-crosoft Office and Adobe Reader will be provided. Furthermore, microphones, a laser pointer, a presenter, and a flip chart will be also provided by the organizers.

To avoid delays during the session, all speakers should test the functionality of their device or the compatibility of their talk with the provided soft- and hardware prior to their session.

Poster Sessions

Tuesday and Wednesday late afternoon are reserved for poster sessions. The size of the poster board is A0 (upright for-mat), pins will be provided.

All poster boards are numbered, please check your number in the list of participants on page 80.

During the poster sessions drinks will be available. The beer is spon-sored by attocube systems AG and LOT-QuantumDesign GmbH.

Meals & Coffee Breaks

Lab Tours Map

Lab Tours (Monday 16:00 h)

Lunch and Dinner – no lunch and dinner are offered at the con-ference site. There are many restaurants in walking distance. On Thursday, the conference dinner will take place at the restaurant Café Reitschule, Königinstraße 34.

Drinks – Soft drinks are available during the coffee breaks.

Coffee Breaks - Coffee/tee/cold drinks and pastries are available during the coffee breaks.

Important: please wear your badge visibly during the coffee breaks. If you forget or lose your badge, please come to the registration desk.

There will be laboratory tours on Monday afternoon at the Max-Planck-Institute of Quantum Optics (MPQ) and the Walter Schottky Institute (WSI).

On Monday afternoon, the laboratory tour will start at 16:00 h. Participants meet at the southern (rear) exit of the final station "Garching Forschungszentrum" of the subway line U6. There will be guides bringing the participants to MPQ

(Hans-Kopfermann-Straße 1, 85748 Garching) and WSI (Am Coulombwall 4, 85748 Gar ching). The participants are split into several groups. After a tour of about 60 min, the three groups will switch locations. The third tour ends at about 18:30 h, so that all participants can visit the two labs and travel back to the city for dinner.

For further clarification, check out the area map on the next page.

Conference Photo (Wednesday 12:30 h)

All conference participants are asked to gather after the Wednesday morning session to take a conference photo. The location will be announced on short notice.

Venue

Lab Tour

Urban Rail Network Munich

8 9RQED 2017 RQED 2017

OverviewOverview

Session 1 ......... 10

Session 2 ......... 15

Session 3 ......... 21

Session 4 ......... 26

Session 5 ......... 32

Session 6 ......... 37

Session 7 ......... 44

Session 8 ......... 49

Session 1

Session 2

Session 4

Session 7

Session 8

Session 5

Session 6

Session 3

An open systems framework to link optical resonators and superconducting circuitsHoward J. Carmichael ..................... 10

Fiber resonators for cavity QED and quantum repeatersWolfgang Alt ................................... 11

Nanocavity QED: from inverse design to implementationsJelena Vuckovic ............................... 12

Quantum nonlinear optics with a single atom strongly coupled to a cavityTatjana Wilk ..................................... 13

Quantum measurement strategies for atoms, photons and electronsMarc Kasevich ................................. 14

Resonator QED using superconducting circuitsFrank K. Wilhelm ............................ 15

Extensible quantum computing with circuit QEDLeonardo DiCarlo ........................... 16

Microwave quantum optics with supercon-ducting circuits: from quantum variational algorithms to sensitive electron spin reso-nance (ESR) measurementsChristopher Eichler ....................... 17

Quantum dynamics of simultaneously mea-sured non-commuting observablesIrfan Siddiqi ..................................... 18

Ultra-strong coupling phenomena beyond the Dicke modelTuomas Jaako ................................... 19

Suppression of light scattering from degenerate fermionsAmita Bikram Deb ............................ 20

Quantum matter built from nanoscopic lattices of atoms and photonsH. Jeff Kimble .................................. 21

Super- and sub-radiance with atoms around an optical nanofiberLuis A. Orozco ................................. 22

On-chip quantum photonics using integrated quantum dot emittersA. Mark Fox ...................................... 23

An on-chip homodyne detector for measuring quantum statesJonathan C. F. Matthews ................ 24

Nonreciprocal quantum optical devices based on chiral interaction of confined light with spin-polarized atomsArno Rauschenbeutel ..................... 25

Cavity QED in the solid stateFabrice P. Laussy .............................. 26

Circuit nano-electromechanicsHans Huebl ...................................... 27

Quantum communication with squeezed microwave statesKirill G. Fedorov ............................. 28

Quantum microwaves with a DC-biased Josephson junctionDenis Vion ........................................ 29

From superradiant criticality to solidification: fundamental limitation of ultrastrong coupling between light and atoms András Vukics .................................. 30

Cryogenic Fabry-Perot resonators for Pur-cell enhanced spin-photon couplingAndreas Reiserer ............................. 31

Quantum memories for scalable quantum photonicsJosh Nunn ........................................ 32

A single ion as quantum receiver for single photonsJürgen Eschner ................................ 33

Modular quantum information processing with superconducting cavity memoriesWolfgang Pfaff ............................... 34

Long-lived memory for a single-photon qubitOlivier Morin ................................... 35

Simultaneous, full characterization of a single-photon stateGlenn S. Solomon ............................ 36

Tools for quantum communicationNorbert Lütkenhaus ...................... 37

How far are we away from a perfect entangled photon source?Fei Ding ............................................. 38

The quantum knitting machine: a quantum dot based device for deterministic production of cluster states of many entangled photonsDavid Gershoni ................................ 39

Quantum relay compatible with existing telecom infrastructure using a semiconduc-tor quantum dotJan Huwer ........................................ 40

Electron spin qubits for quantum networksMete Atatüre ................................... 41

Quantum nonlinear optics with Rydberg-statesThomas Pohl..................................... 44

Contactless photon-photon interactionsCharles S. Adams ............................. 45

Free-space QED with a single Rydberg superatomSebastian Hofferberth ................... 46

Interacting Rydberg polaritons for photonic quantum logicDaniel Tiarks ................................... 47

Strongly interacting Rydberg polaritons and Rydberg atomsVladan Vuletić ........................................ 48

Hybrid optomechanical and superconducting quantum circuitsOskar Painter .................................. 49

Topological control in optomechanical cavitiesJack G. E. Harris .............................. 50

Hybrid quantum systems: coupling diamond color centers to superconducting cavitiesJohannes Majer ............................... 51

Strong coupling of a superconducting resonator to a charge qubitKlaus Ensslin .................................. 52

Advances in chip-integrated nanocavities for spin-photon interfaces, efficient room-temperature single photon sources, and few-photon nonlinear opticsDirk Englund ................................... 53

Oral OralSession Session

10 11

References

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[1] L. S. Bishop et al., Nature Physics 5, 105 (2009)

[2] C. Lang et al., Phys. Rev. Lett. 106, 243601 (2010)

[3] K. W. Murch et al., Nature 502, 211 (2014)

[4] Z. Leghtas et al., Science 347, 853 (2015)

[5] P. Campagne-Ibarcq et al., Phys. Rev. X 6, 011002 (2016)

[6] D. M. Toyli et al. Phys. Rev. X 6, 031004 (2016)

[7] R. Hanbury Brown, “Boffin: A Person-al Story of the Early Days of Radar, Radio Astronomy and Quantum Optics,” (Adam Hilger, Bristol, 1991) pp. 120-121

Although the physics of electromag-netic radiation is explored in the

optical and microwave domains using en-tirely different experimental tools, a sur-prising commonality has emerged at the theoretical and conceptual level, through recent experiments with superconducting circuits and their links to quantum optics [1-6]. In one sense, the development can be seen as a return to beginnings consid-ering that the optical intensity interferom-eter from the 1950s (Hanbury Brown and Twiss effect) was a carryover from Robert Hanbury Brown’s involvement with radar

and radio astronomy. In this regard, it is interesting to recall the reaction to his pro-posal with Richard Twiss [7]: “Our work really put the cat amongst the pigeons. The basic problem was that you can think about light in two different was, as a wave and as particles… to a surprising number of people the idea that the arrival of pho-tons at two different detectors can ever be correlated was not only heretical it was patently absurd, and they told us so in no uncertain terms…If science had a Pope we would have been excommunicated.” In this tutorial I will review the modern

ground that puts any perceived dichot-omy between microWAVES and optical PHOTONS (particles) finally in its place. Recent resonator experiments “see” the particles — even the tiny microwave ones — while the resonators themselves are obviously engineered around waves. I will visit experiments from both sides of the border (optical and microwave), build-ing from an introduction that sets out the conceptual links provided by the theory of Markov open quantum systems.

Howard J. CarmichaelDodd-Walls Center for Photonic and Quantum Technologies, University of Auckland, Private Bag 92019, Auckland, New Zealand

An open systems framework to link optical resonators and superconducting circuits

Atom

Tutorial

References

[1] D. Hunger et al., New J. Phys. 12, 065038 (2010)

[2] J. Gallego et al., Appl. Phys. B 122, 47 (2016)

Fiber resonators are miniature opti-cal cavities directly coupled to op-

tical fibers [1]. They are produced by laser-machining the end faces of cleaved glass fibers into concave mirror shapes, and their small mode volumes and com-

pactness offer distinct advantages for light-matter interaction [2]. I will present practical aspects of fiber resonators, such as mode matching and monolithic fiber resonators, and I will present our experi-ment on strongly coupled rubidium atoms

in the “fast cavity” regime. In the future, such fiber-coupled atomic ensembles may find applications as quantum memories in quantum repeaters for long-distance quantum communication.

J. Gallego, M. Martinez-Dorantes, T. Macha, L. Ratschbacher, D. Pandey, Wolfgang Alt, D. MeschedeInstitute of Applied Physics, University of Bonn, Wegelerstraße 8, 53115 Bonn, Germany

Fiber resonators for cavity QED and quantum repeaters

TUE09:00

TUE10:00

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[1] K. M. Birnbaum et al., Nature 436, 87 (2005)

[2] C. Hamsen, K. N. Tolazzi, T. Wilk, G. Rempe, Phys. Rev. Lett. 118, 133604 (2017)

[3] M. Mücke et al., Nature 465, 755 (2010)

[4] J. A. Souza et al., Phys. Rev. Lett. 111, 113602 (2013)

[5] F. Le Kien, A. Rauschenbeutel, Phys. Rev. A 93, 013849 (2016)

References

Single atom cavity quantum electrody-namics (CQED) in the strong coupling

regime provides an ideal platform for non-linear optical effects at the level of indi-vidual photons. Using a two-level atom, e.g., single-photon [1] and two-photon blockade [2] can be realized, where one or two photons, respectively, block the absorption of further photons. Thus, the light field emitted from the cavity exhib-

its photon statistics with at most single or two photons. Coupling the excited state of the two-level atom to another ground state using a classical control field will in-duce cavity electromagnetically induced transparency [3]. The additional field can be used to optically control the photon statistics [4]. Such control may be extend-ed into the quantum regime by adding a fourth atomic level in N-type configura-

tion that is coupled to a second cavity field. This N-type system would catalyze a direct nonlinear interaction between the two light fields at the level of individual photons. As a result, e.g., mutual blocking [5] or conjunct tunneling of photons may be observed. This may allow for all-optical quantum-nonlinear sensing of photons with photons.

Tatjana Wilk, Christoph Hamsen, Nicolas Tolazzi, and Gerhard RempeMax Planck Institute of Quantum Optics, Hans-Kopfermann-Str. 1, 85748 Garching, Germany

Quantum nonlinear optics with a single atom strongly coupled to a cavity

References

[1] K. Fischer et al, Nature Photonics 10, pp. 163-166 (2016)

[2] J.L. Zhang et al, Nano Letters 16 (1), pp. 212-217 (2016)

[3] M. Radulaski et al, Nano Letters 17 (3), pp 1782–1786 (2017)

[4] M. Radulaski et al, Phys. Rev. A (2017) (arXiv:1612.03261)

[5] A. Piggott, Nature Photonics 9, 374–377 (2015)

Nanophotonic structures that local-ize photons in sub-wavelength vol-

umes are possible today thanks to modern nanofabrication and optical design tech-niques. Such structures enable studies of new regimes of light-matter interaction, quantum and nonlinear optics, and new applications in computing, communica-tions, and sensing.

The traditional solid state nanocavity QED is based on InAs quantum dots inside GaAs photonic crystal cavities, and has enabled a number of experiments includ-ing photon blockade and generation of quantum states of light [1]. Recently, al-ternative material systems have emerged, such as color centers in diamond and silicon carbide [2-3], that could facilitate

scaling to large networks of resonators and emitters and enable interesting ex-periments in multi-emitter cavity QED [4]. Finally, by employing inverse nanopho-tonics design that can efficiently perform physics-guided search through the full pa-rameter space, nanoresonators enabling even stronger light-matter interaction can be designed and implemented [5].

Jelena VuckovicStanford University, Stanford, CA 94305-4088, USA

Nanocavity QED: from inverse design to implementations

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TUE11:30

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OralSessionMarc KasevichStanford University 382 Via Pueblo Mall Stanford, USA

Measurement and interaction-based quantum measurement protocols

based on dispersive cavity-assisted inter-actions will be described. We will show

how these protocols lead to performance improvements for precision atomic sen-sors and to new tests of quantum mechan-ics. We will also describe quantum imag-

ing methods based on repeated coherent interactions in degenerate optical and electron cavities.

Quantum measurement strategies for atoms, photons and electrons

Superconducting integrated circuits have proven to be a fruitful platform

for exploring quantum radiation in reso-nators, specifically allowing to engineer those systems up to the regime of strong interaction and nonlinearity. In this tuto-rial, I will describe basic ideas of circuit

quantization along their main applica-tions: The construction of artificial at-oms and linear cavities, the engineering of their interaction and the development of nonlinear cavities. I will highlight a number of applications enabled by these technologies that specifically rely on these

strong interactions, also highlighting the-oretical methods needed in this strong nonlinear regime. In the end, I will discuss why superconductors are special in this regard and how the microscopic phys-ics of superconductivity relates to circuit quantization.

Frank K. WilhelmSaarland University, 66123 Saarbrücken, Germany

Resonator QED using superconducting circuits

Circuit-QED

Tutorial

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References



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Realizing a logical qubit robust to sin-gle errors in its constituent physical

elements is an immediate challenge for quantum information processing plat-forms. A longer-term challenge will be achieving quantum fault tolerance, i.e., improving logical qubit resilience by in-creasing redundancy in the underlying

quantum error correction code (QEC). In QuTech, we target these challenges in col-laboration with industrial and academic partners. I will present the circuit QED quantum hardware, room-temperature control electronics, and software compo-nents of the complete architecture. I will show the extensibility of each component

to the Surface-17 and -49 circuits needed to reach the objectives with surface-code QEC, and provide an overview of latest de-velopments and spinoffs in quantum sim-ulation. This research is funded by IARPA and Intel Corporation.

Leonardo DiCarloQuTech and Kavli Institutes, Delft University of Technology, The Netherlands

Extensible quantum computing with circuit QED

[1] S. Barret et al., PRL 110, 090501 (2013), J.R. McClean et al., NJP 18, 023023, (2016)

[2] C. Eichler et al., Phys. Rev. X 5, 041044 (2015)

[3] C. Eichler et al. Phys. Rev. Lett. 106, 220503 (2011), C. Eichler et al. PRA 86, 032106 (2012)

[4] C. Eichler et al., PRL 113, 110502 (2014), C. Eichler et al., PRL 107, 113601 (2011)

[5] Y. Liu, et al., Science 347, 258 (2015), J. Stehlik et al., Phys. Rev. Applied 4, 014018 (2015)

[6] Eichler et al., Phys. Rev. Lett. 118, 037701 (2017)

The high level of control achievable over quantized degrees of freedom

has turned superconducting circuits into one of the prime physical architectures for quantum computing and simulation. Along with the continuing progress to-wards building a universal quantum com-puter, the availability of small-scale quan-tum devices has raised interest in hybrid quantum-classical algorithms, in which the power of quantum computation is combined with classical optimization [1]. In my talk, I will present an experimental realization of this idea based on the con-trolled generation of matrix product states

(MPS) - a class of states which has proven extremely powerful as a variational ansatz for numerical simulations. The correla-tion properties of these states are used to experimentally find the ground state of an interacting Bose gas confined in one dimension [2]. Our findings reveal inter-esting connections between the physics of cavity QED, solid state theory, and quan-tum information science. Extensions of the presented approach may be envisaged to also explore dynamical phenomena and discrete lattice models, offering interest-ing interdisciplinary perspectives.

Technologically crucial for our experi-ments have been the development of quantum limited amplifiers [3] and the ability to measure photon statistics in the microwave frequency range [4]. Apart from being essential in our quest to build a practical quantum simulation platform, these technologies turn out very useful for exploring other systems such as spins and electrons in semiconductors [5,6].

Christopher EichlerDepartment of Physics, ETH Zurich, 8093 Zurich, Switzerland

Microwave quantum optics with superconducting circuits: from quantum variational algorithms to sensitive electron spin resonance (ESR) measurements

TUE15:00 TUE

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References




note

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[1] K. Hepp and E. H. Lieb, Ann. Phys. 76, 360 (1973)

[2] Y. K. Wang and F. T. Hioe, Phys. Rev. A 7, 831 (1973)

[3] P. Nataf and C. Ciuti, Nature Com-mun. 1, 72 (2010)

[4] O. Viehmann, J. von Delft, and F. Marquardt, Phys. Rev. Lett. 107, 113602 (2011)

We study effective light-matter in-teractions in a circuit QED system

consisting of a single LC-resonator, which is coupled symmetrically to multiple su-perconducting qubits, see Fig. 1. Starting from a minimal circuit model, we demon-strate that in addition to the usual collec-tive qubit-photon coupling the resulting Hamiltonian contains direct qubit-qubit interactions, which have a drastic effect on the ground and excited state proper-ties of such circuits in the ultra-strong coupling regime. In contrast to a super-radiant phase transition expected from the standard Dicke model [1,2], we find an opposite mechanism, which at very strong interactions completely decouples the photon mode and projects the qubits into a highly entangled ground state, see Fig. 2. These findings resolve previous contro-versies over the existence of superradiant phases in circuit QED [3,4], but they more generally show that the physics of two- or multi-atom cavity QED settings can differ significantly from what is commonly as-sumed.

Tuomas Jaako, Z.-L. Xiang, J.J. García-Ripoll and P. RablVienna Center for Quantum Science and Technology, Atominstitut, TU Wien, Stadionallee 2, 1020 Vienna, AustriaInstituto de Fïsica Fundamental, IFF-CSIC, Calle Serrano 113b, Madrid E-28006, Spain

Ultra-strong coupling phenomena beyond the Dicke model

References

[1] J.B. Hertzberg et al., Nature Physics 6, 213-217 (2010)

[2] N. Didier, J. Bourassa et al., Phys. Rev. Lett. 115, 203601 (2015)

[3] S. Hacohen-Gourgy et al., Nature 538, 491-494 (2016)

Superconducting circuits permit flex-ible engineering of light-matter inter-

actions. Inspired by backaction-evasion measurements in cavity opto-mechanics [1], we explore a richer form of dynamic coupling by driving our superconducting cQED system with symmetric off-resonant tones. Instead of establishing a static coupling of the spin (a superconducting qubit) to the excitation number of the

electromagnetic oscillator (a microwave cavity), as in the dispersive limit of the Jaynes-Cummings interaction, we now couple the spin to the oscillator coordi-nate, thereby displacing the oscillator state (rather than rotating it) in phase-space [2]. Such coupling protects the spin from quantum backaction, enabling sen-sitive quantum metrology and squeezing-enhanced readout. Additionally, by ad-

justing the relative phase of the side-band tones, the orientation of the measurement axis can be readily varied. We apply this tunable measurement protocol to two modes of a microwave cavity coupled to a transmon qubit, thereby realizing the weak continuous measurement of a pair of spin operators as a function of their relative orientation [3].

S. Hacohen-Gourgy, L.S. Martin, E. Flurin, V. Ramasesh, K.B. Whaley and Irfan SiddiqiQuantum Nanoelectronics Laboratory, Center for Quantum Coherent Science, University of California, Berkeley, USA

Quantum dynamics of simultaneously measured non-commuting observables

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References

[1] H. Walther et. al., Cavity quantum electrodynamics, Reports on Progress in Physics, Rep. Prog. Phys. 69, 1325 (2006)

[2] J. Ruostekoski et. al., Optical Line-width of a low-density Fermi-Dirac gas, Phys. Rev. Lett. 82, 4741 (1999)

[3] To be published

[4] Y. Castin et. al., Reabsorption of Light by Trapped Atoms, Phys. Rev. Lett. 80, 5305 (1998)

Purcell effect, the modification of the spontaneous emission rate of photons

from atoms or molecules due to a change in the number of accessible states for pho-tons, lies at the heart of the cavity quan-tum electrodynamics [1]. In a degenerate fermionic gas of atoms, Pauli blocking naturally restricts the processes where an atom scatters to an already occupied cell in the phase space. For low intensity, off-

resonant light that scatters off ultracold fermionic atoms, incoherent scattering events – ones where the atom changes its momentum state – can be strongly sup-pressed due to this Pauli blocking effect, thereby causing a reduction of the Weiss-kopf-Wigner linewidth [2]. We will pres-ent the first experimental observation of this effect, where we scatter off-resonant light from a high atom-number degener-

ate gas of 40-potassium atoms [3]. We used a sensitive heterodyne technique to detect the scattered light and a trapping geometry where the Fermi energy of the system is much greater than the photon recoil energy, while the density is low enough that the effect of photon reabsorp-tion [4] can be minimized.

Amita Bikram Deb1, J. Ruostekoski2 and N. Kjærgaard1 1 Dodd-Walls Centre for Photonic and Quantum Technologies and the Department of Physics, University of Otago, New Zealand.2 Department of Applied Mathematics, University of Southampton, United Kingdom

Suppression of light scattering from degenerate fermions

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References

RQED 2017

[1] J. Douglas, H. Habibian, C.-L.Hung, A. Gorshkov, H. J. Kimble, and D. E. Chang, Nature Photonics 9, 326 (2015)

[2] A. González-Tudela, C.-L. Hung, D. E. Chang, J. I. Cirac, and H. J. Kimble, Nature Photonics 9, 320 (2015)

[3] C.-L. Hung, A. González-Tudela, J. I. Cirac, and H. J. Kimble, PNAS 113, E4946-E4955 (2016)

[4] A. González-Tudela, V. Paulisch, H. J. Kimble, and J. I. Cirac, Phys. Rev. Lett. 118, 213601 (2017)

[5] A. Asenjo-Garcia, M. Moreno-Cardoner, A. Albrecht, H. J. Kimble, and D. E. Chang, Phys. Rev. X (in press, 2017); available at https://arxiv.org/abs/1703.03382

[6] M. T. Manzoni, L. Mathey and D. C. Chang, Nature Comm. (March 2017).

[7] A. Goban, C.-L. Hung, J. D. Hood, S.-P. Yu, J. A. Muniz, O. Painter, and H. J. Kimble, Phys. Rev. Lett. 115, 063601 (2015)

[8] J. D. Hood, A. Goban, A. Asenjo-Garcia, M. Lu, S.-P. Yu, D. E. Chang, and H. J. Kimble, PNAS 113, 10507-10512 (2016)

[9] J. D. Thompson, T. G. Tiecke, N. P. de Leon, J. Feist, A. V. Akimov, M. Gullans, A. S. Zibrov, V. Vuletic, and M. D. Lukin, Science 340, 1202 (2013)

[10] T. Thicke, J. D. Thompson, N. P. de Leon, L. R. Liu, V. Vuletic, and M. D. Lukin, Nature 508, 241 (2014)

New paradigms for optical phys-ics emerge with lattices of atoms

trapped in one and two-dimensional photonic crystals [1–6]. Exemplary ex-perimental platforms include photonic crystal waveguides [7,8] and cavities [9,10]. Owing to their small optical loss and tight field confinement, these na-noscale dielectric devices are capable of mediating long-range atom-atom in-teractions using photons propagating in their guided modes. In a complimentary fashion, long-range interactions between

photons can be mediated by an underly-ing lattice of atoms. Such systems have the potential to provide new tools for quantum phases of light and matter, scalable quan-tum networks, and quantum metrology.

Bringing this future of atom nanophoton-ics to fruition requires the creation of an interdisciplinary toolkit for the control, manipulation, and interaction of atoms and photons with a complexity and scal-ability not currently possible. I will give an overview of theoretical prospects for new

physics and review experimental progress in this nascent field at the interfaces of nano-photonics, atomic physics, quantum optics, and condensed-matter physics.

I gratefully acknowledge funding pro-vided by the Office of Naval Research (ONR) Award No. N00014-16-1-2399, the AFOSR Photonic Quantum Matter MURI, the ONR QOMAND MURI, NSF Grant No. PHY-1205729, and the NSF IQIM Physics Frontiers Center.

H. Jeff KimbleNorman Bridge Laboratory of Physics 12-33, California Institute of Technology, Pasadena, CA 91125, USAJILA, University of Colorado Boulder, 80309 and NIST, CO 80305 USA

Quantum matter built from nanoscopic lattices of atoms and photons

Waveguide

Tutorial

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We report infinite-range interactions between atomic dipoles mediated

by an optical waveguide. This is evi-denced by the collective radiative decay of a single- photon distributed between distant atoms. We use cold 87Rb atoms in the vicinity of a single-mode optical nano-

fiber (ONF) that coherently exchange eva-nescently coupled photons through the ONF mode. We observe super-radiance of a few atoms separated by hundreds of resonant wavelengths where the inter-action is through the ONF. This effect is not possible for atoms separated by more

than a wavelength interacting through free space. The same platform allows us to measure sub-radiance, but this time the atoms interact through free space, pre-senting a novel tool for quantum optics.

P. Solano1, P. Barberis Blostein1,2, F. K. Fatemi3, Luis A. Orozco1 and S. L. Rolston1

1 Joint Quantum Institute, Department of Physics and NIST, University of Maryland, College Park, MD 201742, USA 2 Instituto de Investigaciones en Matemáticas Aplicadas y en Sistemas, Universidad Nacional Autónoma de México , Ciudad Uni-versitaria, 04510, DF, México3 Army Research Laboratory, Adelphi, MD 20783, USA

Super- and sub-radiance with atoms around an optical nanofiber

[1] F. Liu, et al., arXiv. 1706.04422

[2] R.J. Coles, et al., Nature Commun. 7, 11183 (2016)

[3] R.J. Coles et al., Phys. Rev. B 95, 121401(R) (2017)

On-chip quantum photonics relies on the integration of efficient single-

photon sources with advanced quantum-optical circuits. Semiconductor quantum dots (QDs) can exhibit near-ideal single photon emission but suffer from signifi-cant dephasing in on-chip geometries owing to nearby etched surfaces. A long-proposed solution is to use the Purcell effect of an optical nano-cavity to reduce the radiative lifetime to much less than dephasing timescales. However, until now only modest Purcell enhancements have been observed. In this presentation, I will describe recent results on an InGaAs QD

coupled to an H1 photonic crystal nano-cavity under resonant laser excitation [1]. The use of resonant excitation eliminates slow relaxation paths, revealing a highly Purcell-enhanced radiative lifetime of only 22.7 ps. This is measured by apply-ing a novel high-time-resolution double π-pulse resonance fluorescence technique to the QD in a waveguide-coupled photon-ic crystal cavity. Coherent scattering mea-surements confirm the short lifetime and show that the dot exhibits near-radiative-ly-limited coherence. Under π-pulse ex-citation, the waveguide coupling enables demonstration of an on-chip, on-demand

single-photon source exhibiting high purity and indistinguishability without spectral filtering. I will then discuss chiral coupling between QDs and nano-photonic waveguides, which is a manifestation of chiral quantum optics. Experiments dem-onstrating both chiral emission and ex-citon spin initialization will be described [2,3]. These results rely on the precise po-sitioning of dot within the nano-photonic structure, and lay the foundations for de-veloping on-chip spin networks with spin qubits localized in different QDs.

A. Mark FoxDepartment of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, United Kingdom

On-chip quantum photonics using integrated quantum dot emitters

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References


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[1] K. Vogel and H. Risken, Phys. Rev. A, vol. 40, pp. 2847-2849 (1989)

[2] S. Rahimi-Keshari, et al. New Journal of Physics, vol. 13, no. 1, p. 013006 (2011)

[3] S. L. Braunstein and P. van Loock, Rev. Mod. Phys., vol. 77, pp. 513-577, (2005)

[4] A. Politi et al, IEEE Journal of Se-lected Topics in Quantum Electronics, 15, 1673, 2009; Silverstone et al., IEEE Journal of Selected Topics in Quantum Electronics, 22, 390 (2016)

[5] G. Raffaelli et al, arXiv:1612.04676 [quant-ph]

Balanced Homodyne Detection is a mature technique used to measure

quadratures of a quantum electromag-netic field, applied to characterisation of quantum states [1] and quantum pro-cesses [2] for continuous variables (CV) quantum technology [3]. However, use of homodyne detectors on more than a small number of optical modes has so far been limited by the interferometric stability of quantum optical experiments.

Integrated quantum photonics offers ap-proaches to increase the scale and com-plexity of photonic implementations of quantum technology, by minaturising components and providing phase stability in monolithic photonic structures [4].

Here we will discuss capabilities demon-strated in silicon photonics for quantum optical technology. In particular, we will present the realization and demonstra-tion of an integrated homodyne detector

[5] capable of performing measurements of quantum states of light on a Silicon-On-Insulator (SOI) optical chip. The de-vice operates at room temperature and at a wavelength of 1550 nm and shows high speed and low noise, with a 3 dB bandwidth of 150 MHz and a shot-noise clearance of 11 dB. These specifications allowed us to perform homodyne tomog-raphy of coherent states of different am-plitudes with fidelities above 99%.

G. Ferranti, F. Raffaelli, D. H. Mahler, P. Sibson, J. E. Kennard, A. Santamato, G. Sinclair, D. Bonneau, M. G. Thompson, Jonathan C. F. Matthews, Quantum Engineering Technology Labs, H. H. Wills Physics Laboratory and Department of Electrical & Electronic Engineering, University of Bristol, BS8 1FD, United Kingdom

An on-chip homodyne detector for measuring quantum states

References

[1] K. Y. Bliokh et al. Nat. Photon. 9, 796 (2015)

[2] P. Lodahl et al. Nature 541, 473 (2017)

[3] R. Mitsch et al. Nature Commun. 5, 5713 (2014)

[4] C. Junge et al. Phys. Rev. Lett. 110, 213604 (2013)

[5] C. Sayrin et al. Phys. Rev. X 5, 041036 (2015)

[6] M. Scheucher et al. Science 354, 1577 (2016)

The confinement of light in nanopho-tonic structures results in an inherent

link between the light’s local polarization and its propagation direction [1]. Remark-ably, this leads to chiral, i.e., propagation-direction-dependent effects in the emis-sion and absorption of light by quantum emitters [2]. For example, when coupling atoms to an evanescent field, the emis-sion rates into counter-propagating opti-

cal modes can become asymmetric [3]. In our group, we became aware of this chiral light–emitter coupling when studying the interaction of single rubidium atoms with the evanescent part of a light field that is confined by continuous total internal reflection in a whispering-gallery-mode (WGM) microresonator [4]. In the follow-ing, we employed this effect to demon-strate an integrated optical isolator [5] as

well as an integrated optical circulator [6] which operate at the single-photon level and which exhibit low loss. The latter are the first two examples of a new class of nonreciprocal nanophotonic devices which exploit the chiral interaction of quantum emitters with transversally con-fined photons.

J. Volz, B. Albrecht, A. Hilico, C. Junge, R. Mitsch, C. Sayrin, M. Scheucher, D. O’Shea, E. Will, P. Schneeweiss and Arno RauschenbeutelVienna Center for Quantum Science and Technology, Atominstitut, TU Wien, Stadionallee 2, 1020 Wien, Austria

Nonreciprocal quantum optical devices based on chiral interaction of confined light with spin-polarized atoms

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References

RQED 2017 RQED 2017

Session 4Session 4

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sOral OralSession Session

[1] M. Aspelmeyer, T. J. Kippenberg, and F. Marquardt, Rev. Mod. Phys. 86, 1391 (2014)

Micro- and nanomechanical elements are extensively studied due to their

importance in force and mass sensing applications. To access their mechanical response, these vibrating elements are typically integrated into an electronic, electromagnetic, or optical environment. In cavity optomechanics, the interaction of a light field in an optical resonator with the mechanical degree of freedom goes beyond the sole readout functional-ity. Here, the light-matter interaction en-ables the manipulation of the mechanical

state, manifesting itself e.g. in the form of a damped and amplified the mechani-cal motion [1]. This coupling concept can be straightforwardly transferred from the optical to the microwave (MW) regime defining the sub-field of circuit nano-electromechanics. Moreover, quantum information processing based on super-conducting circuits is also at home in this frequency domain. Therefore, nano-elec-tromechanics and superconducting quan-tum circuits use compatible technologies. This paves the way for true hybrid quan-

tum nano-electromechanical systems that enable the investigation of quantum me-chanics in the literal sense.

In my talk, I present a mechanical sensing approach for the investigation of solid-state properties in nano-sized systems, show implementations and consequences of the light-matter interaction in circuit nano-electromechanical systems, and dis-cuss the physics of a hybrid combining superconducting quantum circuits with nanomechanical elements.

Hans HueblWalther-Meißner-Institut, Garching, Germany

Circuit nano-electromechanics

References

[1] H. Carmichael, Atomic tutorial, this venue

[2] J. Vučković, D. Englund, F. Ding, D. Gershoni, A. Shields, G. Solomon, M Atatüre, etc., this venue

[3] K. Wilhelm, Nonlinear tutorial, this venue

[4] E. del Valle et al., Phys. Rev. Lett. 109:183601 (2012)

[5] A. Ulhaq et al., Nat. Photon., 6:238, 2012; M. Peiris et al., Phys. Rev. B, 91:195125, 2015 & Phys. Rev. Lett., 118:030501 (2017)

[6] J.C. López Carreño et al., Phys. Rev. Lett., 115:196402, 2015 & Phys. Rev. A, 94:063825 (2016)

[7] C. Sánchez Muñoz et al., Nat. Phot., 8:550, 2014 & arXiv:1707.03690

While the atomic system [1] has es-tablished the textbook paradigm of

cavity QED, the solid state, in its wake, comes with a series of advantages: the most obvious is for prospective applica-tions, as devices should preferably come on a chip [2]. At a scientific level, this also grows a whole field of its own to accom-modate for the vast range of solid-state effects (phonons, wetting layers, etc.) Not least, this also allows to explore funda-mental variations of the main theme, that restricts itself to parameter ranges and configurations of relevance for atomic experiments. Superconducting qubits, for instance, allow to reach regimes of much stronger nonlinearities [3]. Another ex-ample of fundamental physics pioneered by the solid state in cavity QED comes from frequency-resolved photon correla-tions [4], initially studied for atoms, but that took up a new dimension in semicon-ductors where a two-level system can be

driven more strongly and for longer times [5]. In this tutorial, we give an overview of such solid-state specificities for cavity QED and introduce its Physics of colored-photon correlations, of interest for all

platforms. Implications for applications, from quantum spectroscopy [6] to new generations of quantum light sources [7], will conclude.

Fabrice P. LaussyFaculty of Science and Engineering, University of Wolverhampton, Wulfruna St, WV1 1LY, United Kingdom

Cavity QED in the solid state

The two-photon correlation spectrum of resonance fluorescence—first observed by Peiris et al. with an InAs quantum dot—proved the solid state to be a leading platform for exploring fundamental aspects of quantum optics, in addition to its long-time established superiority for applications (here shown for the case of Franson interfer-ometry). Illustration from Laussy, Nat. Mater., 16:398, 2017.

Solid State

Tutorial

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References

[1] K. G. Fedorov, et al., Phys. Rev. Lett. 117, 020502 (2016)

[2] U. Las Heras, et al., arXiv:1611.10280 (2016)

[3] K. G. Fedorov, et al., arX-iv:1703.05138 (2017)

[4] J. Goetz, et al., Phys. Rev. Lett. 118, 103602 (2017)

Propagating two-mode squeezed mi-crowave states enable applications

of quantum communication and sensing with superconducting quantum circuits [1,2]. In our work, we perform experimen-tal studies of two-mode squeezed (TMS) microwave states [3,4] and use them for demonstration of a basic quantum com-

munication protocol. The TMS states are created by the means of flux-driven Josephson parametric amplifiers and lin-ear circuit elements. We study finite time correlations of the TMS states in order to measure a characteristic time of en-tanglement decay in quantum channels. Further, we investigate robustness of

quantum entanglement and other non-classical correlations, such as quantum discord, to external noise. Finally, we experimentally demonstrate feasibility of a remote state preparation protocol with continuous TMS states and analog feed-forward.

Kirill G. Fedorov1,2, S. Pogorzalek1,2, B. Ghaffari1,2, P. Eder1,2,3, J. Goetz1,2, M. Fischer1,2, E. Xie1,2, A. Marx1, F. Deppe1,2,3 and R. Gross1,2,3

1 Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany2 Physik-Department, Technische Universität München, 85748 Garching, Germany3 Nanosystems Initiative Munich (NIM), Schellingstraße 4, 80799 München, Germany

Quantum communication with squeezed microwave states

References

[1] M. Hoffheinz et al., Phys. Rev. Lett. 106, 217005 (2011)

[2] In preparation

[3] M. Westig et al., arXiv:1703.05009 (2017)

Tunneling of a Cooper pair through a dc-biased Josephson junction is pos-

sible only if collective excitations (pho-tons) are produced in the rest of the circuit to conserve the energy. The prob-ability of tunneling and photon creation, well described by the theory of dynami-cal Coulomb blockade, increases with the

coupling strength between the tunneling charge and the circuit mode, which scales as the mode impedance. Using very sim-ple circuits with only one or two high im-pedance series resonators, we first show the equality between Cooper pair tunnel-ing rate and photon production rate [1]. Then we demonstrate a blockade regime

for which the presence of a single photon blocks the next tunneling event and the creation of a second photon [2]. Finally, using two resonator with different fre-quencies, we demonstrate photon pair production [3], two-mode squeezing, and entanglement between the two modes leaking out of the resonators.

C. Rolland1, O. Parlavecchio1, A. Peugeot1, M. Westig1, I. Moukharski1, B. Kubala2, C. Altimiras1, M. Hofheinz1, P. Simon3, P. Roche1, P. Joyez1, P. Bertet1, Denis Vion1, J. Ankerhold2, D. Esteve1 and F. Portier1

1 NanoElectronics and Quantronics groups, SPEC, CEA, CNRS, Université Paris-Saclay, CEA-Saclay, 91191 Gif-sur-Yvette Cedex, France2 Institue for complex Quantum Systems, University of Ulm, 89068 Ulm, Germany3 Laboratoire de Physique des Solides, Université Paris-Saclay, 91405 Orsay, France

Quantum microwaves with a DC-biased Josephson junction

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[1] Hensen et al. Nature 526, 682 (2015)

[2] Kalb*, Reiserer*, Humphreys* et al. Science 356, 928 (2017)

[3] Bogdanovic et al. Appl. Phys. Lett. 110, 171103 (2017)

[4] Miyazono et al. Appl. Phys. Lett. 108, 011111 (2016)

References

Spins in solids can exhibit strong opti-cal transitions and exceptional coher-

ence properties. This makes them a prom-ising system towards the realization of global quantum networks. Pioneering ex-periments have shown entanglement be-tween two remote spins, associated with the Nitrogen-vacancy (NV) center in dia-mond, over a distance of 1.3 km [1]. How-ever, exploring the full potential of quan-tum networks requires to further increase the separation and number of entangled particles. In this respect, two major chal-lenges have to be addressed. First, one has to overcome inevitable imperfections in the control of the spins via quantum er-

ror correction. I will present first results in this direction, namely the distillation of entanglement between remote spins [2].

The second challenge is that the efficiency of photonic quantum network links has to be increased by orders of magnitude. In our current approach, a deterministic spin-photon interface is implemented by embedding NV spins in micrometer-thin crystals into Fabry-Perot resonators. We recently achieved a Finesse up to 12000 even when operating at cryogenic temper-ature [3]. This should allow us to increase remote entanglement rates between spins by more than three orders of magnitude.

Further enhancement, in particular over long distances, requires to convert the emitted photons to the telecommunica-tion frequency band where the absorption of glass fibers is minimal. A potential al-ternative is to use Erbium spins, which is the only known impurity emitting in this frequency regime. Recent experiments have shown Purcell enhanced emission [4]. However, the 14 ms long lifetime of the excited states of Erbium requires to strongly improve the cooperativity. I will present the current status of a new experi-ment that tries to achieve this via Fabry-Perot resonators with mode volumes ap-proaching a single cubic wavelength.

Andreas Reiserer1,2, B. Merkel1, N. Wilson1, V. Crépel1, S. Bogdanović2, S. v. Dam2, C. Bonato2, L. Coenen2, A.-M. Zwerver2, B. Hensen2, M. Liddy2, T. Fink3, M. Lončar4, R. Hanson2

1 Quantum Networks Group, Max-Planck-Institute of Quantum Optics, Garching, Germany2 QuTech and Kavli Institute of Nanoscience, Delft University of Technology, The Netherlands3 Institute of Quantum Electronics, ETH Zurich, Switzerland4 John A. Paulson School of Engineering and Applied Sciences, Harvard University, USA

Cryogenic Fabry-Perot resonators for Purcell enhanced spin-photon coupling

We present a solution to the long-standing problem whether the

superrandiant (Dicke) phase-transition critical point can be reached in the origi-nal setting of the Dicke model: electric dipoles (atoms) in the electromagnetic field. For this we have to revisit some fun-damentals of the modeling of light-matter interaction. First, by a generalization and modification of the Power–Zineau–Wool-

ley picture, we build such a framework for the quantum electrodynamics of atoms as is free from the A-square and P-square problems, and valid in arbitrary confined geometries [1–2]. Second, by using this framework, we give an upper bound for the achievable coupling strength between light and atoms in the ultrastrong regime [2]. Supported by a scaling argument val-id in the presented QED picture, we argue

that the superradiant phase transition is an indication of a mundane phase tran-sition, namely, solidification [2]. Finally, we study the effect of the remainder of instantaneous atom-atom (depolarizing) interaction on the phase transition finding a shift of the critical point from the pure Dicke [3].

T. Griesser, András Vukics, and P. DomokosWigner Research Centre for Physics of the Hungarian Academy of Sciences P.O. Box 49, H-1525 Budapest, Hungary

From superradiant criticality to solidification – fundamental limitation of ultrastrong coupling between light and atoms

References

[1] A. Vukics et al., Phys. Rev. Lett. 112, 073601 (2014)

[2] A. Vukics et al., Phys. Rev. A 92, 043835 (2015)

[3] T. Griesser et al., Phys. Rev. A 94, 033815 (2016)

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Optical signals can support quantum states without noise at room tem-

perature, and can be sent over distance in fibres and free space links. However the great promise of photonics as a platform for quantum information processing can-not be realised without strong light-matter interactions. While the main theme of this

meeting focusses on such enhanced inter-actions to implement giant non-linearities between photons, an alternative route is to engineer material systems that can store light, providing the capability to buffer and actively synchronise non-determinis-tic all-optical interactions such as entan-glement heralding and swapping. In this

tutorial I will review various approaches to light storage. I will present some of the results from our group, working towards broadband, room-temperature memories, alongside some very significant advances from other groups around the world.

Josh NunnDepartment of Physics, University of Bath, United Kingdom

Quantum memories for scalable quantum photonics

[1] M. Schug et al., Phys. Rev. A 90, 023829 (2014)

[2] P. Müller, J. Eschner, Appl. Phys. B 114, 303 (2014).

[3] C. Kurz et al.,Nat. Commun. 5, 5527 (2014)

[4] C. Kurz et al.,Phys. Rev. A 93, 062348 (2016)

[5] A. Lenhard et al., Phys. Rev. A 92, 063827 (2015)

[6] J. Brito et al., Appl. Phys. B. (2016), 122:36

[7] S. Kucera et al., in preparation

[8] A. Lenhard et al., Opt. Express 25, 11187 (2017)

We are developing a comprehensive set of experimental tools, based

on trapped single ions and single pho-tos, that enable controlled generation, storage, transmission, and conversion of photonic qubits in quantum networks. Specifically, we implemented a program-mable atom-photon interface, employing the controlled quantum interaction be-tween a single trapped 40Ca+ ion and sin-gle photons [1,2]. Depending on its mode

of operation, the interface serves as a bi-directional atom-photon quantum state converter (receiver and sender mode), as a source of entangled atom-photon states (entangler mode), or as a quantum frequency converter of single photons [3,4] (converter mode). It lends itself par-ticularly to integrating ions with single photons or entangled photon pairs from spontaneous parametric down-conversion (SPDC) sources [5,6]. As an experimen-

tal application of the receiver mode, we demonstrate the transfer of entanglement from an SPDC photon pair to atom-photon pairs with high fidelity [7]. It is realized by heralded absorption and storage of a single photonic qubit in a single ion. We extend our quantum network toolbox into the telecom regime by quantum fre-quency conversion of ion-resonant single photons [8].

Jürgen EschnerExperimentalphysik, Universität des Saarlandes, 66123 Saarbrücken, Germany

A single ion as quantum receiver for single photons

Memory

Tutorial

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The cavity quantum electrodynamics in the optical domain constitutes a fasci-

nating playground for the development of a quantum information processing toolbox as shown by recent demonstrations rang-ing from remote entanglement generation to quantum gates. This talk will concen-trate on a very important building block of future quantum technologies: the storage of a photonic qubit. In contrast to the stor-age of a single excitation, storage of a qu-

bit is a more demanding task as it needs two features: First, an efficient light-mat-ter interface and second, protection of the qubit against decoherence. These two de-mands have been efficiently demonstrated in some systems, but always separately. In our setup, based on a single 87Rb atom in a high finesse cavity, the coherence time of the storage has now been increased by three orders of magnitude. This has been achieved by mapping the qubit to and fro

between two atomic configurations. As a result, we can efficiently write and re-trieve a polarization qubit in and from and atom, respectively, and store it there for a duration as long as 100 ms. This consti-tutes an important milestone towards the realization of global scale quantum com-munication including quantum repeaters.

Olivier Morin, M. Körber, S. Langenfeld, A. Neuzner, S. Ritter and G. RempeMax-Planck-Institut für Quantenoptik, Hans-Kopfermann-Strasse 1, 85748 Garching, Germany

Long-lived memory for a single-photon qubit

[1] Reagor et al., Phys. Rev. B 94, 014506 (2016)

[2] Ofek et al., Nature 536, 441 (2016)

[3] Kimble, Nature 453, 1023 (2008)

[4] Pfaff et al., Nature Phys., Advance Online Publication, doi: 10.1038/nphys4143 (2017)

[5] Cirac, Zoller, Kimble, and Mabuchi, Phys. Rev. Lett. 78, 3221 (1998)

Superconducting cavities can store microwave fields for several millisec-

onds, naturally making them a promising system for realizing memories for su-perconducting circuits. In this talk, I will present our approach for using cavities that are coupled to Josephson qubits as long-lived quantum memories. We show that 3D cavities made from bulk super-conductors can be used to store quantum states on millisecond time scales [1]. We further demonstrate that these systems are capable of processing and protecting

quantum information encoded in complex multiphoton states [2].

An important consideration is how it is possible to scale up to large quantum in-formation processing architectures from individual cavity systems. We aim to real-ize a modular architecture in which indi-vidual network nodes exchange quantum information through propagating photons in transmission lines [3]. As a crucial step towards this vision we show that we can, rapidly and on-demand, convert

multiphoton quantum states from a cav-ity memory into propagating channels [4]. This enables quantum state transfer and entanglement between remote cavity nodes [5].

Our cavity system can thus serve as the backbone in a microwave quantum net-work. It can be used to realize error-pro-tected distribution of quantum informa-tion, and thus provides a route towards a modular quantum computer.

Wolfgang Pfaff, C. Axline, L. Burkhart, M. Reagor, L. Frunzio, L. Jiang, M. Devoret and R. SchoelkopfDepartment of Applied Physics and Yale Quantum Institute, Yale University, New Haven, CT, 06520, USA

Modular quantum information processing with superconducting cavity memories

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36

References

RQED 2017note

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OralSession

[1] T. Thomay, et al., arXiv:1701.07040, (2017)

As single-photon sources become more mature and are used more of-

ten in quantum information, communica-tions and measurement applications, the details of their characterization become more important. Single-photon-like light is often characterized by the device’s photon flux — its brightness, and two quantum properties: the suppression of multi-photon components and the photon indistinguishability. While it is desirable to obtain these quantities from a single measurement, currently two or more mea-surements are used.

Here we simultaneously determine the brightness, the suppression of multi-pho-ton content, the indistinguishability, and the statistical distribution of Fock states to third order for a quantum light source [1]. We use the light emitted from a single InAs quantum dot resonant with a planar microcavity and pumped by a pulsed-laser side-coupled to the cavity. However, the measurement is not source specific. The measurement uses a pair of two-photon (n = 2) number-resolving detectors, here modeled using single-photon detectors. Using a Fisher-information analysis, we show that the new method extracts more

information per experimental trial than a conventional measurement for most input states, and is particularly more efficient for statistical mixtures of photon states. Furthermore, n ≥ 3 number-resolving de-tectors provide no additional advantage in the single-photon characterization. Thus, using this n = 2, number- resolving detec-tor scheme will provide new advantages in a variety of quantum optics measure-ments and system characterization.

T. Thomay1, S. V. Polyakov2, O. Gazzano1, E. Goldschmidt1, V. Loo1, T. Huber1, and Glenn S. Solomon1,2

1Joint Quantum Institute, National Institute of Standards and Technology, & University of Maryland, Gaithersburg, MD, USA2National Institute of Standards and Technology, Gaithersburg, MD, USA

Simultaneous, full characterization of a single-photon state

References

[1] V. Scarani, H. Bechmann-Pasquinuc-ci, N.J. Cerf, M. Dusek, N. Lütkenhaus, M. Peev, Rev. Mod. Phys. Vol 81, p. 1301

[2] J.M. Arrazola, N. Lütkenhaus, Phys. Rev. A, 89, 062305 (2014)

[3] J. M. Arrazola, D. Touchette, Quan-tum advantage on information leakage for equality, arXiv 1607.07516

[4] M. Takeoka, S. Guha, M.M. Wild, Nature Communications 5, 5235 (2014)

[5] S. Pirandola, R. Laurenza, C. Ottavi-ani, L. Banchi, Nature Communications 8, 15043 (2017)

[6] S. Muralidharan, J. Kim, N. Lütken-haus, M. D. Lukin, L. Jiang, Phys. Rev. Letters, Vol. 112, 250501 (2014)

[7] D. Luong, L. Jiang, J. Kim, N. Lütken-haus, Applied Physics B, 122, 96, (2016)

Quantum Communication offers quali-tative advantages, such as quantum

key distribution [1], but also quantita-tive advantages, such as more efficient data comparison [2] and other protocols with a quantum communication and in-formation [3] complexity advantage, se-cure multi-party computation and so on. In this tutorial I will lay out the tasks at hand, and then describe the tools that we

need in actual implementations. Some tasks might be readily completed by us-ing non-orthogonal states and non-com-muting measurements, and here simple laser pulses already may do the trick. Other tasks require more complex signal structures, including multi-party entan-gled states. A very important issue is that of transmission loss which poses funda-mental bounds on quantum transmissions

[4,5] which can be overcome by quantum repeaters. We will discuss the various ar-chitectures of quantum repeaters [6] and the requirement for hardware implemen-tations. An important aspect is a proper benchmarking of quantum repeaters, in-cluding stepping stones to beat the funda-mental bounds [7].

Norbert Lütkenhaus Institute for Quantum Computing & Department of Physics and Astronomy, University of Waterloo, Canada

Tools for quantum communication

Communication

Tutorial

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[1] Y. Huo et al. Nature Physics 10, 46 (2014)

[2] J. Zhang et al. Nature Communica-tions 6, 10067 (2015)

[3] Y. Chen et al. Nature Communications 7, 10387 (2016)

[4] R. Keil et al. Nature Communications 8, 15501 (2017)

[5] E. Chekhovich et al. Nature Materials accepted (2017)

[6] J. Zhang et al. Nano Letters 13, 5808 (2013)

[7] Y. Zhang et al. Nano Letters 16, 5785 (2016)

Entangled photon sources are im-portant in quantum information sci-

ences. Nowadays, they are mainly based on the probabilistic SPDC processes in non-linear materials. Self-assembled semiconductor quantum dots (QDs) are a promising candidate for the deterministic generation of entangled photons. More-over, compared to other systems, QDs have an undeniable advantage of being compatible with industrial technologies.

Unfortunately, more than 20 years have passed since the first report on QDs and we do not see yet any realistic applica-tions of QD based quantum light sources, which is due to the fact that these sources are far from being ideal and several criti-cal challenges need to be solved. In this talk I will try to convince you that the fu-ture is very promising for QDs. I will in-troduce our recent efforts in developing a QD-based entangled photon source with

the best possible performances. The high yield (100%), high fidelity (up to 0.9), wavelength tunability, together with the demonstrations of electrical injection and on-chip integration, will eventually make these source an ideal workhorse for the quantum photonic applications.

Fei DingInstitute for Solid State Physics, Leibniz University Hannover, GermanyInstitute for Integrative Nanosciences, IFW Dresden, Germany

How far are we away from a perfect entangled photon source?

References

[1] H. J. Briegel, Science 354, 416 (2016)]

[2] I. Schwartz et al, Science 354, 434, (2016)

Photonic cluster states are a resource for quantum computation based sole-

ly on single-photon measurements [1]. We use semiconductor quantum dots to deterministically generate long strings of polarization-entangled photons in a clus-ter state, using periodic timed excitation

of a precessing matter qubit spin. In each period, an entangled photon is added to the cluster state formed by the matter qu-bit and the previously emitted photons. In our prototype device, the qubit is the quantum dot confined dark exciton, and it produces strings of hundreds of photons

in which the entanglement persists over five sequential photons [2].

*Work done in collaboration with Ido Schwartz, Dan Cogan, Emma Schmidgall, Yaroslav Don, Liron Gantz, Oded Kenneth and Netanel Lindner.

David Gershoni*The Physics Department and the Solid State Institute, Technion, Haifa, 32000, Israel

The quantum knitting machine: a quantum dot based device for deterministic production of cluster states of many entangled photons

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[1] B. C. Jacobs et al., Phys. Rev. A 66, 52307 (2002)

[2] C. Varnava et al., npj Quantum Infor-mation 2, 16006 (2016)

[3] J. Huwer et al., arXiv:1704.07765 (2017)

References

Quantum relays [1] are one possible solution to extend the range of pres-

ent quantum cryptography systems and future optical quantum networks. In this approach, teleportation of photonic in-put quantum bits is used to effectively reduce noise in long-distance photon-transmission scenarios. Entanglement sources based on non-linear processes have a long history in photonic teleporta-tion experiments, but the number statis-tics of these sources follow a Poissonian distribution. Multi-photon events increase error rates and require operation at very low intensities and implementation of

sophisticated security protocols. In con-trast, semiconductor quantum dots are a promising alternative entangled-photon source, with true single-photon emission enabling intrinsically secure implementa-tions of quantum relays [2]. In this talk, we investigate a semiconductor-based quantum relay which is operating at standard telecom wavelength (O-band) [3], therefore being compatible with ex-isting telecom-fiber infrastructure. For implementation of a standard 4-state QKD-protocol with weak coherent input states, the system achieves mean fidelities above 88%. In addition, we demonstrate

robustness against frequency detuning of the input state, making it compatible with standard off-the-shelf telecom laser sources. Further characterization reveals teleportation for arbitrary input states opening up the route for future operation with enhanced communication protocols. The results are an important advance in demonstrating feasibility of semiconduc-tor light sources for the development of infrastructure-compatible quantum-com-munication technology. The use of sub-Poissonian entanglement sources might bare practical advantages, especially for security-sensitive applications.

References

[1] R. Stockill et al., Phys. Rev. Lett. 119, 010503 (2017)

[2] G. Ethier-Majcher et al., arX-iv:1706.07749 (2017)

Optically active spins confined in sol-ids, such as semiconductors and

diamond, provide interesting and rich physical systems. Their inherently meso-scopic nature leads to a multitude of dy-namics within the solid-state environment of spins, charges, vibrations and light.

While the quantum optics has provided the toolbox for advanced spectroscopic investigations for these interaction mech-anisms, it also offers solution possibilities for their detrimental effects for the reali-sation of operational quantum devices. Of these systems, semiconductor quantum

dots offer perhaps the brightest photons along with a reasonable spin coherence. In this talk, I will provide a snapshot of the progress in the optical interconnection of quantum dot spin qubits [1], as well as steps towards qubit protection through reservoir engineering [2].

Mete Atatüre Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, United KingdomJan Huwer1, M. Felle1,2, R. M. Stevenson1, J. Skiba-Szymanska1, M. B. Ward1, I. Farrer3, R. V. Penty2, D. A. Ritchie3, and A. J. Shields1

1 Toshiba Research Europe Limited, Cambridge Research Laboratory, 208 Cambridge Science Park, Milton Road, Cambridge, United Kingdom2 Centre for Advanced Photonics and Electronics, University of Cambridge, J.J. Thomson Avenue, Cambridge, CB3 0FA, United Kingdom3 Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge, CB3 0HE, United Kingdom

Electron spin qubits for quantum networksQuantum relay compatible with existing telecom infrastructure using a semiconductor quantum dot

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08:45 Welcome Address

SESSION 1 SESSION 3 SESSION 5 SESSION 709:00 Howard J. Carmichael

An open systems framework to link optical reso-nators and superconducting circuits

H. Jeff KimbleQuantum matter built from nanoscopic lat-tices of atoms and photons

Josh NunnQuantum memories for scalable quantum photonics

Thomas PohlQuantum nonlinear optics with Rydberg-states

10:00 Wolfgang AltFiber resonators for cavity QED and quantum repeaters

Luis A. OrozcoSuper- and sub-radiance with atoms around an optical nanofiber

Jürgen EschnerA single ion as quantum receiver for single photons

Charles S. AdamsContactless photon-photon interactions

10:30 Coffee Break Coffee Break Coffee Break Coffee Break

11:00 Jelena Vuckovic Nanocavity QED: from inverse design to imple-mentations

A. Mark FoxOn-chip quantum photonics using integrated quantum dot emitters

Wolfgang PfaffModular quantum information processing with superconducting cavity memories

Sebastian HofferberthFree-space QED with a single Rydberg superatom

11:30 Tatjana WilkQuantum nonlinear optics with a single atom strongly coupled to a cavity

Jonathan C. F. MatthewsAn on-chip homodyne detector for measuring quantum states

Olivier MorinLong-lived memory for a single-photon qubit

Daniel TiarksInteracting Rydberg polaritons for photonic quantum logic

12:00 Marc KasevichQuantum measurement strategies for atoms, photons and electron

Arno RauschenbeutelNonreciprocal quantum optical devices based on chiral interaction of confined light with spin-polarized atoms

Glenn S. SolomonSimultaneous, full characterization of a single-photon state

Vladan VuletićStrongly interacting Rydberg polaritons and Rydberg atoms

12:30 - 14:00

Lunch Break Lunch Break Lunch Break Lunch Break

SESSION 2 SESSION 4 SESSION 6 SESSION 814:00 Frank K. Wilhelm

Resonator QED using superconducting circuits

Fabrice P. LaussyCavity QED in the solid state

Norbert Lütkenhaus Tools for quantum communication

Oskar PainterHybrid optomechanical and superconducting quantum circuits

15:00 Leonardo DiCarloExtensible quantum computing with circuit QED

Hans HueblCircuit nano-electromechanics

Fei DingHow far are we away from a perfect entangled photon source?

Jack G. E. HarrisTopological control in optomechanical cavities

15:30 Coffee Break Coffee Break Coffee Break Coffee Break

16:00 Lab TourLab tours at MPQ and WSI / ZNN at Garching Forschungszentrum

(until ~18:30)

Christopher EichlerMicrowave quantum optics with superconducting circuits: from quantum variational algorithms to sensitive electron spin resonance (ESR) measure-ments

Kirill G. FedorovQuantum communication with squeezed microwave states

David GershoniThe quantum knitting machine: a quantum dot based device for deterministic production of cluster states of many entangled photons

Johannes MajerHybrid quantum systems: coupling diamond color centers to superconducting cavities

16:30 Irfan SiddiqiQuantum dynamics of simultaneously measured non-commuting observables

Denis VionQuantum microwaves with a DC-biased Josephson junction

Jan HuwerQuantum relay compatible with existing telecom infrastructure using a semiconductor quantum dot

Klaus EnsslinStrong coupling of a superconducting resonator to a charge qubit

17:00 Tuomas JaakoUltra-strong coupling phenomena beyond the Dicke model

András VukicsFrom superradiant criticality to solidification – fundamental limitation of ultrastrong coupling between light and atoms

Mete Atatüre Electron spin qubits for quantum networks

Dirk EnglundAdvances in chip-integrated nanocavities for spin-photon interfaces, efficient room-temper-ature single photon sources, and few-photon nonlinear optics

17:20 Amita Bikram DebSuppression of light scattering from degenerate fermions

Andreas ReisererCryogenic Fabry-Perot resonators for Purcell enhanced spin-photon coupling

17:40-

19:15

Poster Session 1Beer sponsored by attocube systems

Poster Session 2

Beer sponsored by LOT-QuantumDesign 19:00 Conference Dinner

Café Reitschule Königinstraße 34

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References

[1] K. Fischer et al, Nature Photonics 10, pp. 163-166 (2016)

[2] J.L. Zhang et al, Nano Letters 16 (1), pp. 212-217 (2016)

[3] M. Radulaski et al, Nano Letters 17 (3), pp 1782–1786 (2017)

[4] M. Radulaski et al, Phys. Rev. A (2017) (arXiv:1612.03261)

[5] A. Piggott, Nature Photonics 9, 374–377 (2015)

The realization of electromagnetically induced transparency (EIT) in Ryd-

berg gases has emerged as a promising route toward achieving few-photon optical nonlinearities. While EIT provides strong light-matter coupling under low-loss con-ditions, the strong interactions between

Rydberg-states can be used to generate nonlinearities that are strong enough to operate on the level of single photons.

In this talk, I will introduce the basic con-cepts behind this approach. Starting from a classical optics perspective that reveals

the underlying interaction and blockade effects, we will consider their conse-quences in the quantum regime, includ-ing a discussion of potential applications and recent experiments. Some perspec-tives and current challenges will also be described.

Thomas PohlAarhus University, Ny Munkegade 120, 8000 Aarhus C, Denmark

Quantum nonlinear optics with Rydberg-states

References

[1] A. Mohapatra et al, , Phys Rev Lett. 98, 113003 (2007)

[2] O. Firstenberg, C. S. Adams, and S. Hofferberth, J Phys B 49, 152003 (2016)

[3] H. Busche et al., Nature Phys. 13, 655 (2017)

The experimental demonstration of electromagnetically induced trans-

parency (EIT) involving highly-excited Rydberg atoms [1] opened the door to a new field of quantum non-linear optics mediated by dipolar interactions between highly-excited Rydberg atoms [2]. A unique feature of Rydberg quantum optics is the ability of photons to interact without ever being in the same medium. Recently, we demonstrated repulsion between two

photons separated by 15 times their wave-length [3]. Each photon experiences a po-sition dependent refractive index induced by the photon stored in the adjacent me-dium, as illustrated in the Fig. 1.

Such long-range interactions between photons provide an interesting platform for scalable multichannel photonic devic-es, or quantum simulation of strongly-cor-related many-body dynamics using light.

Charles S. AdamsJoint Quantum Centre (JQC) Durham-Newcastle, Department of Physics, Durham University, South Road, Durham DH1 3LE, United Kingdom

Contactless photon-photon interactions

Fig 1.:Propagation of photons (red) through two independent media (grey) separated by a distance, d. The photons are stored in collective superpositions involving highly-excited Rydberg states which interact via long-range van der Waals interactions. The interactions imprint a phase gradient on the super-position state (shown below) leading to a deflection of the outgoing photons. The inset shows the case of a single channel.

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[1] O. Firstenberg, C. Adams, S. Hoffer-berth, J. Phys. B 49, 152003 (2016)

[2] A. Paris-Mandoki, C. Braun, J. Kumlin, C. Tresp, I. Mirgorodskiy, F. Christaller, H. P. Büchler, S. Hofferberth, arXiv:1705.04128 (2017)

[3] C. Tresp, C. Zimmer, I. Mirgorods-kiy, H. Gorniaczyk, A. Paris-Mandoki, S. Hofferberth, Phys. Rev. Lett. 117, 223001 (2016)

Mapping the strong interaction be-tween Rydberg excitations in ul-

tracold atomic ensembles onto single photons enables the realization of optical nonlinearities which can modify light on the level of individual photons. This novel approach forms the basis of a growing Rydberg quantum optics toolbox, which already contains photonic logic building-blocks such as single-photon sources, switches, transistors, and conditional pi-phase shifts [1].

Here, we discuss our recent experiments coupling an optical medium smaller than a single Rydberg blockade volume to a few-photon probe field. Due to the large number of atoms in the blockaded volume and the efficient coupling to the probe light mode, we achieve coherent coupling between the probe field and the effective Rydberg “superatom” even if the probe pulse contains only a few photons. This enables us to study the dynamics of a single two-level system strongly coupled

to a quantized propagating light field in free space [2].

Furthermore, by controlling the dephasing between the internal degrees of freedom of the superatom, we realize a free-space single-photon absorber, which determin-istically absorbs exactly one photon from an input pulse. We show that this system can be used for the subtraction of one photon from the input pulse over a wide range of input photon numbers [3].

A. Paris-Mandoki1, C. Braun1, J. Kumlin2, C. Tresp1, I. Mirgorodskiy1, F. Christaller1, H. P. Büchler2, Sebastian Hofferberth1

1 Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Dk-5230 Odense, Denmark2 Institut für Theoretische Physik III and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Germany

Free-space QED with a single Rydberg superatom

[1] J. D. Pritchard et al. Phys. Rev. Lett. 105, 193603 (2010)

[2] S. Baur et al. Phys. Rev. Lett. 112, 073901 (2014)

[3] H. Gorniaczyk et al. Phys. Rev. Lett. 113, 053601 (2014)

[4] D. Tiarks et al. Phys. Rev. Lett. 113, 053602 (2014)

[5] D. Tiarks et al. Science Advances 2, e1600036 (2016)

[6] J. D. Thompson et al. Nature 542, 206 (2017)

The strong dipole-dipole interaction between Rydberg atoms has enabled

remarkable experimental success rang-ing from quantum information processing with single atoms to observation of ex-otic many-body states. Interestingly, the interaction between Rydberg excitations can also be used to create a large effec-tive interaction between photons. To this end, one addresses Rydberg states with electromagnetically induced transpar-

ency. This creates a quasiparticle, called Rydberg polariton, which consists of a photonic component and a co-propagat-ing atomic Rydberg excitation. The large interactions between the Rydberg compo-nents manifest themselves in the form of giant optical nonlinearities [1].

A central goal in the field of Rydberg polaritons is the realization of photonic quantum logic. This line of research has

seen impressive progress in the last few years, including the demonstration of sin-gle-photon transistors [2,3,4] and the ob-servation of large conditional phase shifts at the single photon level [5,6]. We report on our recent progress on using Rydberg polaritons for photonic quantum logic.

Daniel Tiarks, S. Schmidt, T. Stolz, S. Dürr, G. RempeMax-Planck-Institut für Quantenoptik, Hans-Kopfermann-Str. 1, 85748 Garching, Germany

Interacting Rydberg polaritons for photonic quantum logic

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References

[1] J.D. Thompson, T.L. Nicholson, Q.-Y. Liang, S.H. Cantu, A.V. Venkatramani, S. Choi, I.A. Fedorov, D. Viscor, T. Pohl, M.D. Lukin, and V. Vuletić, Nature 542, 206-209 (2017)

By coherently coupling light to Ryd-berg excitations in a dense atomic

medium, it is possible to realize tunable strong long-range interaction between individual traveling Rydberg polaritons. By implementing exchange collisions be-

tween selected Rydberg levels, we realize a robust π/2 collisional phase shift that is determined by the interaction symmetry rather than the precise experimental pa-rameters. This may enable advances to-wards more general symmetry-protected

many-body states. I will also discuss re-cent advances on coherent dynamics in a many-atom Rydberg quantum simulator using deterministically prepared arrays of single atoms.

Q.-Y. Liang1, J.D. Thompson1,2, T.L. Nicholson1, S.H. Cantu1, A.V. Venkatramani1,2, S. Choi2, I.A. Fedorov1, M.D. Lukin2 and Vladan Vuletić1

1 Department of Physics and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 021392 Department of Physics, Harvard University, Cambridge, MA 02138, USA

Strongly interacting Rydberg polaritons and Rydberg atoms

[1] M. Eichenfield, J. Chan, R. Camacho, K. J. Vahala, and O. Painter, Nature, doi:10.1038/nature08524, October 19 (2009)

[2] M. H. Devoret and R. J. Schoel-kopf, Science, doi:10.1126/science.1231930v339, March 8 (2013)

[3] K. Fang, J. Luo, A. Metelmann, M. H. Matheny, F. Marquardt, A. A. Clerk, and Oskar Painter, Nature Physics, doi:10.1038/nphys4009, January 16 (2017)

I will present recent ideas and devel-opments involving the integration of

optomechanical crystals, which couple light and sound [1], and electronic super-conducting quantum circuits which have large quantum nonlinearities that can be exploited for quantum information pro-cessing applications [2]. Utilizing the sili-con-on-insulator (SOI) wafer platform, we have made key advances in the fabrication and integration of extremely low-loss mi-

crowave phonon structures and low-loss microwave superconducting resonators. These technical advancements offer sev-eral intriguing opportunities for quantum information processing and networking with phonons, photons, and electrons in an integrated, wafer-scale platform. After providing an introduction to optomechani-cal crystals, the focus of my talk will be on three recent highlights of our work in this area: (i) nonreciprocal photon transport

and amplification arising from synthetic magnetic flux and reservoir engineering in an optomechanical crystal circuit [3], (ii) demonstration of a hypersonic (GHz) silicon optomechanical crystal resonator with Q-factor = 40 billion at mK tempera-tures, and (iii) development of transmon qubits on SOI with excellent coherence properties (T1 = 3.5 μs, T2

* = 2.2 μs).

B. Berger, P. Dieterle, K. Fang, M. Fang, M. Kalaee, A.Keller, J. Luo, G. MacCabe, M. Matheny, H. Ren and Oskar PainterKavli Nanoscience Institute, Institute for Quantum Information and Matter, and the Thomas J. Watson, Sr., Laboratory of Applied Physics, California Institute of Technology, Pasadena CA 91125 USA

Hybrid optomechanical and superconducting quantum circuits

Hybrid

Tutorial

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[1] W. D. Heiss., Euro. Phys. J. D 7, 1 (1999)

[2] H. Xu et al. Nature 537, 80 (2016)

[3] H. Xu et al, ArXiv 1703.07374 (2017)

[4] M. V. Berry et al. J. Phys. A 44, 435303 (2011)

[5] R. Uzdin et al. J. Phys. A 44, 435302 (2011)

The adiabatic theorem states that if a system of lossless coupled oscillators

is subject to a slow perturbation, then any excitation that is initially stored in an eigenmode remains in that eigenmode as it evolves under the perturbation. As a consequence, a closed-loop operation (i.e., in which the system’s Hamiltonian is modified and then returned to its ini-tial value) does not change the system’s state, except for an overall phase shift. In contrast, it was noted recently [1] that the situation is qualitatively different if the

oscillators are damped. In particular, it was predicted that a closed-loop adiabatic operation which encloses an exceptional point (EP, a degeneracy in the complex ei-genvalues of a damped system) will swap the excitations between two modes. It was also predicted that a closed-loop adiabatic operation which does not enclose an EP will not result in a swap. This is an ex-ample of topological control: an operation whose outcome is determined by a topo-logical property such as the enclosing of a particular point. We demonstrate this

topological control by swapping energy between two mechanical modes of a di-electric membrane; the control sequence is implemented by driving an optical cav-ity to which the membrane is coupled [2]. We also show that a simple modulation scheme can be used to extend this to-pological control to modes which do not possess an EP [3]. As a result, this type of control can be implemented between es-sentially any modes of any optomechani-cal system. Lastly, we discuss the nonre-ciprocal nature of these operations [4,5].

H. Xu, D. Mason, Luyao Jiang and Jack G. E. HarrisDepartment of Physics & Department of Applied Physics & Yale Quantum Institute, Yale University, New Haven, CT, USA

Topological control in optomechanical cavities

[1] R. Amsüss, Ch. Koller, T. Nöbauer, S. Putz, S. Rotter, K. Sandner, S. Schnei-der, M. Schramböck, G. Steinhauser, H. Ritsch, J. Schmiedmayer, and J. Majer, Phys. Rev. Lett. 107, 060502 (2011)

[2] S. Putz, D. O. Krimer, R. Amsuss, A. Valookaran, T. Nobauer, J. Schmied-mayer, S. Rotter, and J. Majer, Nature Physics 10, 720-724 (2014)

[3] S. Putz, A. Angerer, D.O. Krimer, R. Glattauer, W.J. Munro, S.Rotter, J. Schmiedmayer, and J. Majer, Nature Photonics 11, 36-39 (2017)

[4] T. Astner, S. Nevlacsil, N. Peterschof-sky, A. Angerer, S. Rotter, S. Putz, J. Schmiedmayer, and J. Majer, Phys. Rev. Lett. 118, 140502 (2017)

References

Hybrid quantum systems based on spin-ensembles coupled to super-

conducting microwave cavities are prom-ising candidates for robust experiments in cavity quantum electrodynamics (QED) and for future technologies employing quantum mechanical effects. In particu-lar the electron spins hosted by nitrogen-vacancy centers in diamond [1]. The main source of decoherence in this systems is inhomogeneous dipolar spin broadening and a full understanding of the complex dynamics is essential and has not been addressed in recent studies yet. We inves-tigate the influence of a non-Lorentzian

spectral spin distribution in the strong coupling regime of cavity QED. We show experimentally how the so-called cavity protection effect influences the decay rate of coherent Rabi oscillation by varying the coupling strength in our experiment [2]. We then demonstrate how the Rabi oscillation amplitude can be enhanced by two orders of magnitude by pulsing the strongly coupled system matching a spe-cial resonance condition.

Furthermore, we show that by burning narrow spectral holes into a spin ensem-ble we create long-lived collective dark

states [3]. We observe long-lived Rabi oscillations with high visibility and a de-cay rate that is a factor of 40 smaller than the spin ensemble linewidth and thereby more than a factor of three below the pure cavity dissipation rate.

Additionally, I will discuss the possibil-ity of coupling spin ensembles over large distances using the cavity as a quantum bus [4].

Johannes MajerVienna Center for Quantum Science and Technology, Atominstitut, TU Wien, 1020 Vienna, AustriaWolfgang Pauli Institut c/o Fak. Mathematik Univ. Wien, Oskar Morgensternplatz 1, 1090 Vienna

Hybrid quantum systems: coupling diamond color centers to superconducting cavities

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We demonstrate the strong coupling limit with individual electronic

charges in GaAs double quantum dots by using the enhancement of the electric component of the vacuum fluctuations by increasing the resonator impedance Zr beyond the typical 50 Ω of a standard coplanar waveguide. We have realized a frequency-tunable microwave resonator with impedance Zr ~ 1.8 kΩ using the large inductance Lr ~ 50 nH of a SQUID array combined with a small stray capacitance

Cr ~ 15 fF. Its resonance frequency, and thus also its impedance, is tunable by ap-plying a small magnetic field using a mm-sized coil mounted on the sample holder. The frequency tunability of the resonator is particularly useful in this context, as it allows for the systematic study of its inter-action with semiconductor nanostructures without changing their electrical bias conditions. In the resonant regime, we resolve the vacuum Rabi mode splitting of 238 MHz at a resonator linewidth 12

MHz and a charge qubit decoherence rate of 40 MHz extracted independently from microwave spectroscopy in the disper-sive regime. In addition we demonstrate a semiconductor charge qubit coupled to a TiNbN superconducting resonator oper-ated at magnetic fields up to 5 T. This way spin effects such as spin blockade in the double quantum dot can be investigated using microwave resonators.

A. Stockklauser, P. Scarlino, A. Landig, J. Koski, S. Gasparinetti, C. Kraglund Andersen, C. Reichl, W. Wegscheider, T. Ihn, A. Wallraff and Klaus EnsslinSolid State Physics, ETH Zurich, Switzerland

Strong coupling of a superconducting resonator to a charge qubit

References

[1] S. Mouradian, N. H. Wan, T. Schröder, and D. Englund, Appl. Phys. Lett. 111, 021103 (2017)

[2] S. L. Mouradian and D. Englund, APL Photonics 2, 046103 (2017)

[3] M. Schukraft, J. Zheng, T. Schröder, S. L. Mouradian, M. Walsh, M. E. Trusheim, H. Bakhru, and D. R. Englund, APL Photonics 1, 020801 (2016)

[4] T. Schroder, W. M. Z. J, S. Moura-dian, L. Li, G. Malladi, H. Bakhru, M. Lu, A. Stein, M. Heuck, and D. Englund, To Appear in Adv. Optical Materials (2017)

[5] T. Schröder, M. E. Trusheim, M. Walsh, L. Li, J. Zheng, M. Schukraft, A. Sipahigil, R. E. Evans, D. D. Sukachev, C. T. Nguyen, J. L. Pacheco, R. M. Cama-cho, E. S. Bielejec, M. D. Lukin, and D. Englund, Nat. Commun. 8, 15376 (2017)

[6] M. Heuck, M. Pant, and D. R. Englund, in Conference on Lasers and Electro-Optics (OSA, Washington, D.C., n.d.), p. FTu4C.7

[7] H. Choi, M. Heuck, and D. Englund, Phys. Rev. Lett. 118, 223605 (2017)

[8] A. Nysteen, D. P. S. McCutcheon, M. Heuck, J. Mørk, and D. R. Englund, Phys. Rev. A 95, 062304 (2017)

Optical resonators play a central role in several photonic quantum technolo-

gies. This talk will describe recent advanc-es in three areas: spin-photon interfaces based on a new fabrication process for di-

amond photonic crystal nanocavities [1,2] and spatially aligned nitrogen vacancy (NV) [3,4] or silicon vacancy (SiV) [5] col-or centers; efficient single photon sources based on heralded four-wave mixing in

a feedback-controlled silicon nanocavity [6]; and cavity concepts for few-photon-level optical nonlinearities [7,8].

Sara Mouradian1, Noel Wan1, Tim Schroeder1,2, Michael Walsh1, Matthew Trusheim1, Hyongrak Choi1, Marco Schukraft1, Dara McCutcheon3, Jasper Mørk4, Mikkel Heuck1,4, Mihir Pant1 and Dirk Englund1

1 Research Laboratory for Electronics, Massachusetts Institute of Technology, USA2 Niels Bohr Institute, University of Copenhagen, Denmark3 Quantum Engineering Technology Labs, University of Bristol, United Kingdom4 DTU Fotonik, Department of Photonics Engineering, Technical University of Denmark

Advances in chip-integrated nanocavities for spin-photon interfaces, efficient room-temperature single photon sources, and few-photon nonlinear optics

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Poster PosterSession Session

References

The giant atom regime of quantum acousticsG. Andersson .............. 56

Quantum networks in diver-gence-free circuit QEDA. Parra-Rodríguez ..... 56

Beating the limits in qubit reset with initial correlationsD. Basilewitsch .......... 57

Tools for multi-photon scatter-ing experiments: Tomography protocol and effect of dephas-ing noiseT. Ramos ...................... 57

Probing spin-phonon coupling at the quantum limit using light-matter interactionT. Astner ...................... 58

Fluorescence state detection of single atoms on a non-cycling transitionB. Wang ....................... 58

Single atoms coupled to a near-concentric cavityC. H. Nguyen ................ 59

Tunable-range, photon-me-diated interactions between atoms using a multimode cavityK. Ballantine .............. 59

Towards single neutral atoms in crossed fiber cavitiesJ. D. Christesen ........... 60

Keldysh meets Lindblad: dephasing assisted gain and loss in higher order perturba-tion theoryC. Müller ..................... 60

Cold-atom based implemen-tation of the quantum Rabi modelA. Dareau ..................... 61

Strong coupling between photons of two light fields mediated by one atomK. N. Tolazzi ................ 61

Quantum optical circulator controlled by a single chirally coupled atom E. Will ......................... 62

Observation of the pho-ton-blockade breakdown phase transitionA. Dombi ............... 62

Cavity-controlled chemi-cal reactions of ultracold atomsT. Kampschulte .... 63

Two-atom quantum gate using an optical resona-torB. Hacker .............. 63

Manipulation of quantum nonlinearities in single atom cavity EIT systemG. Li ...................... 64

Two-photon bundles from a single two-level systemL. Hanschke ......... 64

Dipolar systems in the ultra strong coupling regimeD. De Bernardis ... 65

Helium ion modified luminescence and valley depolarization of atomically thin MoS2M. Kaniber ........... 65

In situ characterization of qubit control lines: a qubit as a vector network analyzer M. Jerger .............. 66

Atom-light interactions in a few-mode optical nanofiberJ. Du ...................... 66

Enhanced optical activity of atomically thin MoSe2 proximal to nanoscale plasmonic slot-waveguides M. Blauth ............ 67

Towards the realisation of an atom trap in the evanescent field of a microresonatorL. Masters ........... 67

Analysis of decoherence mechanisms in a single-atom quantum memoryM. Korber ............ 68

Design considerations of cryo-RFICs for super - conducting qubits readout...M. Mehrpoo ......... 68

Enhanced spontaneous emission from quantum dots coupled to metal nano-antennasA. Nolinder .......... 69

Quantum correlations in propagating two-mode squeezed microwave statesS. Pogorzalek ...... 70

Solid-state ensemble of highly entangled photon sources at rubidium atomic transitionsR. Keil .................. 70

Coupling multiple-spin qubits via a microwave resonatorM. Russ ................ 71

Transmon qubits meet cavity electromechanicsP. Schmidt ............ 71

On-chip transduction of microwave and optical signals using nanome-chanical resonators M. Wulf ............... 72

Optically probing spin qubit coherence without coherent control T. Simmet ............. 72

Modular segmented ion trap with an integrated optical CavityS. Ragg ................. 73

Engineering a diamond spin-qubit with a nano-electro-mechani-cal systemM. Gündogan ....... 73

Investigation of coher-ence times of phospho-rus dimers in 28Si at millikelvin temperaturesS. Weichselbaumer ... 74

Generation of atomic Bell states in a cavity via quantum state carvingS. Welte ............... 74

Optical nanofiber-based cavity induced by periodic air-nanohole arraysW. Li ..................... 75

Two-photon blockade in an atom-driven cavity QED systemT. Wilk ................. 75

Towards quantum inter-ference between distant entangled-photon emit-tersM. Zopf ................. 76

Quantum simulators for open quantum systems using quantum Zeno dynamicsS. Patsch .............. 76

Discrete-time reservoir engineering with entan-gled bath and stabilizing squeezed statesZ. Miao ................ 77

Entanglement routing in an ion-trap-based quantum nodeD. A. Fioretto ..... 78

Towards strong coupling of a trapped ion to a fiber cavityM. Teller ............ 78

Long-lived quantum emitters in hBN-WSe2 van-der-Waals hetero-structures J. Wierzbowski ... 79

Sensing weak micro-wave signals by quantum ControlA. M. Waeber ...... 79

OverviewSession 1 Session 2

Poster Session 1: Tuesday, 17:40 - 19:15

Poster Session 2: Wednesday, 17:40 - 19:15

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Poster PosterSession SessionSession 1Session 1

Tools for multi-photon scattering experiments: Tomography protocol and effect of dephasing noise

We present new tools for character-izing multi-photon scattering ex-

periments in current microwave or optical photonic platforms.

First, we develop an experimental proto-col to interrogate the multi-photon scat-tering matrix of any quantum object in-teracting with propagating photons [1]. It requires coherent state wavepacket in-puts and homodyne detection at the scat-terer’s output, and provides simultaneous information about multiple —elastic and inelastic— segments of the scattering matrix. Additionally, our method is resil-ient to detector noise and its errors can be made arbitrarily small by combining experiments at various weak laser pow-ers. As an example, we apply the protocol to reconstruct the nonlinear two-photon scattering matrix of a single two-level sys-

tem coupled to a one-dimensional wave-guide.

Second, we study how correlated dephas-ing noise is manifested in this type of scat-tering experiements. This is of particular importance to implementations with su-perconducting circuits, where dephasing is currently the main source of decoher-ence. We consider models of correlated gaussian noise, 1/f noise, and telegraph noise, and study how the single-photon transmission lineshapes are modified on each case. This may give a deeper insight to the underlying noise processes that are manifested in scattering experiments, as well as a more precise knowledge about the properties of the quantum scatterers, and the nonlinear coherent processes me-diated by them.

Tomás Ramos, and Juan José García-RipollInstituto de Física Fundamental IFF-CSIC, Calle Serrano 113b, Madrid 28006 Spain

Fast and reliable reset of a qubit is a key prerequisite for any quantum

technology. For real world open quan-tum systems undergoing non-Markovian dynamics, reset implies not only purifica-tion, but in particular erasure of initial cor-

relations between qubit and environment. Here, we derive optimal reset protocols using a combination of geometric and numerical control theory. For factorizing initial states, we find a lower limit for the entropy reduction of the qubit as well as

a speed limit. The time-optimal solution is determined by the maximum coupling strength. Initial correlations, remarkably, allow for faster reset and smaller errors. Entanglement is not necessary.

Daniel Basilewitsch1, Rebecca Schmidt2,3, Dominique Sugny4,5, Sabrina Maniscalco2,3 and Christiane P. Koch1

1 Theoretische Physik, Universität Kassel, D-34132 Kassel, Germany2 Turku Centre for Quantum Physics, Department of Physics and Astronomy, University of Turku, FIN-20014 Turku, Finland3 Center for Quantum Engineering, Department of Applied Physics, Aalto University School of Science, FIN-00076 Aalto, Finland4 Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 5209 CNRS-Université de Bourgogne Franche Comté, F-21078 Dijon Cedex, France5 Institute for Advanced Study, Technische Universität München, D-85748 Garching, Germany

Beating the limits in qubit reset with initial correlations

Superconducting circuits can be con-sidered as one of the leading quan-

tum platforms for quantum technologies, as is the case of quantum computers and quantum simulators. With growing sys-tem complexity, it is of crucial impor-tance to develop scalable circuit models that contain the minimum information to predict the behaviour of the physical sys-tem. Based on microwave engineering methods, divergent and non-divergent Hamiltonian models in circuit quantum electrodynamics have been proposed to

explain the dynamics of superconducting quantum networks coupled to infinite-dimensional systems, as transmission line resonators and general impedance envi-ronments. Here, we systematically study common linear coupling configurations between networks and infinite-dimension-al systems. In this manner, the coupling parameters between their components correctly manifest their natural decou-pling at high frequencies, a feature that is behind the misleading prediction of diver-gent quantities, including the Lamb-shift.

Furthermore, we show the requirements to correctly separate infinite-dimensional coupled systems in local bases. Moreover, we compare our analytical results with other analytical and approximate methods available in the literature. Finally, we pro-pose several applications of these general methods to analog quantum simulation of multi-spin-boson models in the non-perturbative coupling regimes, or the pre-diction of effective convergent qubit-qubit coupling through a transmission line.

Adrián Parra-Rodríguez1, E. Rico1,2, E. Solano1,2, I. L. Egusquiza3

1 Department of Physical Chemistry, University of the Basque Country UPV/EHU, Apartado 644, 48080 Bilbao, Spain2 IKERBASQUE, Basque Foundation for Science, Maria Diaz de Haro 3, 48013 Bilbao, Spain,3 Department of Theoretical Physics and History of Science, University of the Basque Country UPV/EHU, Apartado 644, 48080 Bilbao, Spain

Quantum networks in divergence-free circuit QED

We study the interaction of supercon-ducting artificial atoms with surface

acoustic wave (SAW) phonons on piezo-electric substrates [1]. This “quantum acoustic” platform enables experiments analogous to quantum optics, where the superconducting circuit that forms the ar-tificial atom has characteristic dimensions

much larger than the wavelength of the coupled acoustic field. By exploiting the slow propagation velocity of SAW, artifi-cial atoms can be designed that couple to a propagating field at two distant points such that the SAW travel time between them has to be taken into account. Pho-nons emitted into the acoustic channel by

such a “giant atom” may interact with the atom again leading to revivals in the ex-cited state population [2]. A dispersively coupled coplanar waveguide microwave resonator allows us to read-out the excit-ed state population of the qubit, thereby enabling us to perform its time-domain characterisation. We observe a non-ex-ponential energy relaxation and study the phonon scattering properties of giant atoms placed on GaAs, with a resonance frequency in the 2-2.5 GHz range.

[1] M. Gustafsson et al. Science 346, 207-211 (2014)

[2] L. Guo et al. Phys. Rev. A 95 (2017)

References

Gustav Andersson1, L. Guo2, T. Aref1, M. K. Ekström1, B. Suri1, A. Ask1, G. Johansson1 and P. Delsing1

1 Department of Microtechnology and Nanoscience (MC2), Chalmers University of Technology, SE-41296 Gothenburg, Sweden2 Institute for Theoretical Solid State Physics, Karlsruhe Institute of Technology (KIT), D-76131 Karlsruhe, Germany

The giant atom regime of quantum acoustics

References

[1] Multi-photon scattering tomogra-phy with coherent states, T. Ramos, J.J. García-Ripoll, arXiv:1705.10211

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References

[1] A. J. Kollar et al., N. J. Phys. 17, 043012 (2015)

[2] A. J. Kollar et al., Nat. Commun. 8, 14386 (2017)

Controllable interactions between par-ticles are a key component of quan-

tum simulation and of exploring quantum many-body physics. We demonstrate that, by using a nearly confocal optical reso-nator [1,2], one may engineer tunable-range interactions between condensates of ultra-cold atoms. We show that the experimental data matches the theoreti-cally expected form of the interaction, giving a clear understanding of the range and form of the this interaction. Near con-focality, we derive a closed form for the effective interaction potential which de-cays exponentially at small distances. The length scale of this decay depends on the detuning of the pump beam and the cav-ity mode spacing, both easily controllable. Together with previous advances in quan-

tum simulation in multimode cavity QED, this flexible interaction opens the way to studying emergent many-body phenom-ena beyond mean-field theory in a confo-cal cavity.

Kyle Ballantine1, V. Vaidya2, Y. Guo2, R. Kroeze2, B. Lev2 and J. Keeling1

1 Scottish University Physics Alliance, University of St Andrews, St Andrews, United Kingdom2 Stanford University, Stanford, USA

References

[1] A. Reiserer and G. Rempe, Rev. Mod. Phys. 87, 1379 (2015)[2] K. Durak et al., New Journal of Phys-ics 16, 103002 (2014)

[3] C. H. Nguyen et al. arXiv:1706.01256 [quant-ph] (2017)

[4] A. Wickenbrock et al., Phys. Rev. A 87, 043817 (2013)

To date, the requirements to obtain strong atom-photon coupling in Cav-

ity Quantum Electrodynamics (CQED) have been presumed to be cavities with a high finesse and small mode volumes. Though having demonstrated remarkable results and progress [1], such cavities with limited optical access, high reflectiv-ities coating and close distance between mirrors pose a challenge for scaling up and embedding other systems with CQED such as ion traps. An alternative approach of employing a near-concentric cavity de-signs with strong focusing modes [2].

In this work, we present the proof-of-concept experiment of coupling a single atom 87Rb to a 11 mm long near-concen-

tric cavity with a finesse of 140. The cavity length is 1.65 μm shorter than the concen-tric point and accommodates a focusing mode of approximately 5μm beam waist. We observe the normal mode splitting of the cavity spectrum under the present of the trapped single 87Rb atoms. The CQED parameters of our system are found to be (g,k,γ)/2π=(5,45,3) MHz [3]. By upgrad-ing the Finesse to a modest value of 1000 we expect to achieve strong coupling in the next experiment. The success of this experiment promises to facilitate the scal-ing up of quantum network and could open many unexplored atomphoton ex-periments in strong coupling multimode CQED [4].

Chi Huan Nguyen, A. N. Utama, M. Steiner, and C. KurtsieferCentre for Quantum Technologies, University, 3 Science Drive 2, 117543 Singapore

Single atoms coupled to a near-concentric cavity

State-selective fluorescence is widely used to readout the internal state of

atoms or ions. Applications range from optical clocks to quantum information processing. To reach a high accuracy, many scattered photons are required. Any loss channel leading to a dark state stops the fluorescence and reduces the fidelity. Therefore, standard fluorescence detec-

tion is only applicable for a few internal states that can be excited via a cycling transition, like the |52S1/2,F=2> state in 87Rb. We now theoretically and experi-mentally study schemes for the detection of the |52 S1/2,F=1> state in 87Rb for which a cycling transition does not exist. Our schemes are based on cavity-enhanced fluorescence and alternating probe-beam

configurations. By optimizing the con-trol sequence, we currently achieve a hyperfine-state-detection fidelity of 96% for a 12 μs probing interval. Theoretical concepts for further optimization will be presented.

Bo Wang, M. Körber, S. Langenfeld, O. Morin, A. Neuzner, S. Ritter and G. Rempe Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Str. 1, 85748, Garching, Germany

References

[1] R. Hanson and D. D. Awschalom, Nature 453, 1043-1049 (2008)[2] T. Astner, S. Nevlacsil, et. al.; Phys. Rev. Lett. 118, 140502 (2017)

[3] A. Angerer, T.Astner, et. al.; Appl. Phys. Lett. 109, 089901 (2016)

[4] T. Astner, J. Gugler, et. al.; arXiv: 1706.09798 (2017)

The negatively charged nitrogen-va-cancy (NV) center in diamond [1] has

attracted significant attention for pos-sible applications in quantum information tasks. It possesses long lifetimes (T1) and spin-phase coherence times (T2) even at room temperature. In hybrid architec-tures robust coupling between remote ensembles demonstrated that these spin species may open the opportunity for sol-id-state quantum information transfer [2]. To exploit all features of this spin system, sound knowledge of spin-environment in-teraction is necessary.

In the solid state environment, the most fundamental process by which an excited spin ensemble transfers energy to the surrounding is governed by longitudinal relaxation processes. These processes are usually driven by spin-phonon in-teraction. However, the so far available methods did not allow us to investigate on spin relaxation at temperatures where quantum effects become relevant. Gain-ing knowledge of this relaxation phenom-enon is of utterly importance since the longitudinal relaxation time (T1) provides the ultimate limit of phase coherence of a quantum emitter.

Here we show a method to study the lon-gitudinal spin-lattice relaxation of large ensembles of NV spins in diamond. Our experiment is based on a cavity quantum electrodynamics scheme where we use a novel 3D lumped element resonator [3]. The spin ensemble is in the strong cou-pling regime and in the experiment we measure the spin-lattice relaxation below the single phonon limit. There quantum fluctuations become important and pro-vide the ultimate upper bound for T1 [4]. Remarkably, we find that the low phonon-ic density of states at the NV transition frequency enables the spin polarization to survive over macroscopic timescales of up to 8 h [4].

To understand the fundamental mecha-nism we additionally present a theoretical model that describes the direct spin pho-non coupling mechanism and calculate the relaxation rate ab initio based on den-sity functional theory (DFT).

The figure shows and illustration of the cavity spin-phonon system to measure spin lattice relaxation. The picture shows the used superconducting 3D lumped element resonator with Q-factors up to 500.000 at 3 GHz.

Thomas Astner, J. Gugler, A. Angerer, S. Wald, S. Putz, N. J. Mauser, M. Trupke, H. Sumiya, S. Onoda, J. Isoya, J. Schmiedmayer, P. Mohn and J. MajerFaculty of Physics, Institute of Atomic and Subatomic Physics, TU Wien, Stadionallee 2, 1020 Wien, Austria

Probing spin-phonon coupling at the quantum limit using light-matter interaction

(001)

Vs-ph

Phononbath

Spinensemble

Cavity

gN

Fluorescence state detection of single atoms on a non-cycling transition

Tunable-range, photon-mediated interactions between atoms using a multimode cavity

Fig. 1. (a) Schematic of experimental setup with multimode cavity photons mediating interaction between two atomic condensates. (b) Effective atom-atom interaction length as function of detuning from TEM00 mode (Δ0) and mode spacing (ε). Dots are extracted from experiment and dashed lines are a fit to theory.

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References

[1] P. Schneeweiss, A. Dareau, and C. Sayrin, arXiv:1706.07781 (2017)

The interaction of a two-level system (TLS) with a single bosonic mode is

one of the most fundamental processes in quantum optics. Microscopically, it is described by the quantum Rabi model (QRM). Here, we propose an implementa-tion of this model based on single trapped cold atoms [1]. The TLS is implemented using atomic Zeeman states, while the atom’s vibrational states in the trap rep-resent the bosonic mode. The coupling is mediated by a suitable fictitious magnetic field pattern. We show that all important system parameters, i.e., the emitter--field detuning and the coupling strength of the emitter to the mode, can be tuned over a wide range. Remarkably, assuming realis-

tic experimental conditions, our approach allows one to explore the regimes of ultra-strong coupling, deep strong coupling, and dispersive deep strong coupling. The states of the bosonic mode and the TLS can be prepared and read out using stan-dard cold-atom techniques. Moreover, we show that our scheme enables the imple-mentation of important generalizations, namely, the driven QRM, the QRM with quadratic coupling as well as the case of many TLSs coupled to one mode (Dicke model). The proposed cold-atom based implementation will facilitate experi-mental studies of a series of phenomena predicted for the QRM in extreme, so far unexplored physical regimes.

P. Schneeweiss, Alexandre Dareau, and C. SayrinVienna Center for Quantum Science and Technology, Atominstitut, TU Wien, Stadionallee 2, 1020 Vienna, Austria

Cold-atom based implementation of the quantum Rabi model

References

[1] Liu, Petersson, Stehlik, Taylor, and Petta, Phys. Rev. Lett. 113, 036801 (2014)

[2] Liu, Stehlik, Eichler, Gullans, Taylor, and Petta, Science 347, 285–287 (2015)

[3] Gullans, Liu, Stehlik, Petta, and Tay-lor, Phys. Rev. Lett. 114, 196802 (2015)

[4] Müller and Stace, Phys. Rev. A 95 013847 (2017)

Motivated by correlated decay pro-cesses driving gain, loss and lasing

in driven semiconductor quantum-dots [1–3], we develop a theoretical technique using Keldysh diagrammatic perturbation theory to derive a Lindblad master equa-tion that goes beyond the usual second or-der perturbation theory. We demonstrate the method on the driven dissipative Rabi model, including terms up to fourth order in the interaction between the qubit and both the resonator and environment. This results in a large class of Lindblad dissi-pators and associated rates which go be-yond the terms that have previously been

proposed to describe similar systems. All of the additional terms contribute to the system behaviour at the same order of perturbation theory. We then apply these results to analyse the phonon-assisted steady-state gain of a microwave field driving a double quantum-dot in a reso-nator. We show that resonator gain and loss are substantially affected by dephas-ing- assisted dissipative processes in the quantum-dot system. These additional processes, which go beyond recently proposed polaronic theories, are in good quantitative agreement with experimental observations [4].

Clemens Müller and T. M. StaceARC Centre of Excellence for Engineered Quantum Systems, The University of Queensland, Brisbane, Australia

Keldysh meets Lindblad: dephasing assisted gain and loss in higher order perturbation theory

References

[1] D. Hunger et al., New J. Phys. 12, 065038 (2010)

[2] M. Uphoff et al., Appl. Phys. B 112, 46 (2016)

Cavity quantum electrodynamics pro-vides a rich toolbox for the inves-

tigation of fundamental phenomena in quantum physics through increased light-matter coupling which enables many in-triguing applications in quantum informa-tion processing. One method to further increase the light-matter coupling for a neutral atom trapped in a cavity is to de-crease the cavity mode volume. Limits on the reduction of the cavity mode volume imposed by traditional manufacturing processes of the cavity mirrors have been overcome with the introduction of fiber cavities [1], where fiber end facets are machined by means of CO2 laser ablation.

Besides small mode volumes and larger coupling rates, fiber cavities also allow for new cavity geometries due to their small-er dimensions, including coupling a sin-gle emitter to two independent and per-pendicular cavity modes. We are currently setting up a new experiment consisting of two crossed fiber cavities which real-izes this unique cavity geometry and also constitutes an important step towards the implementation of an integrated quantum repeater [2]. We will present the current status and future plans for our apparatus including fabrication results of elliptical and spherical fiber mirrors.

Joseph Dale Christesen, D. Niemietz, M. Brekenfeld, S. Ritter and G. RempeMax-Planck-Institut für Quantenoptik, Hans-Kopfermann-Str. 1, 85746 Garching, Germany

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The key ingredient for many applica-tions in quantum information pro-

cessing is the controlled interaction be-tween individual photons. In classical nonlinear optical media, typical interac-tion strengths are negligible at the level of individual quanta. However a signifi-cant interaction between single photons can be reached in quantum systems. An ideal platform for this is provided by cav-ity quantum electrodynamics (cQED) with its strong light matter coupling. There,

two research fields are evolving: linear quantum networking where the system interacts sequentially with individual photons in separate temporal modes and quantum-nonlinear optics where the sys-tem interacts simultaneously with two or more photons of the same mode. In con-trast, engineering a cQED system with direct nonlinear coupling between two different cavity modes where the atom only catalyzes the interaction between photons in these two distinct light fields

is still an outstanding challenge. Here, we demonstrate how two optical fields cou-pled to different longitudinal modes of a cavity can be brought to interaction using a single four-level atom. While each field by itself is transmitted unaltered, already a single photon in one mode suppresses the transmission of photons in the other mode. In analogy to strong coupling be-tween cavity and atom in standard cavity quantum electrodynamics, we refer to this new effect as strong coupling of photons.

K. Nicolas Tolazzi, C. Hamsen, T. Wilk, G. RempeMax Planck Institute of Quantum Optics, Hans-Kopfermann-Str. 1, 85748 Garching, Germany

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References

[1] J. Ulmanis et al., Chem. Rev. 112, 4890 (2012)

[2] J. Volz et al., Nature 475, 210 (2011)

[3] I. D. Leroux, M. H. Schleier-Smith, and V. Vuletić, Phys. Rev. Lett. 104, 073602 (2010)

Ultracold molecules can be formed from ultracold atoms by photoasso-

ciation [1] involving a spontaneous emis-sion process, resulting in a number of final states. Here we want to use strong coupling to an optical cavity to selectively enhance the creation of a certain final state, see Figure 1. During this process, a photon will be emitted into the cavity mode which can be detected. A collective enhancement of the effect would enable “superradiant chemistry”.

In addition, we want to use the cavity for direct, state-selective and non-destructive optical Detection [2] of ultracold mol-ecules. Moreover, collective probing of an ensemble of molecules could induce non-classical correlations, such as squeezed states [3] of a molecular degree of free-dom.

For the experiment, we are integrating a high-finesse optical microcavity into an existing Rb BEC apparatus where Rb2 molecules can be be produced by mag-neto- and photoassociation.

Tobias Kampschulte1, S. Rupp1, G.Liu1, W. Schoch1, J. Hecker Denschlag1, J. Schnabel2, A. Köhn2

1 Institute of Quantum Matter, Ulm University, 89069 Ulm, Germany2 Institute for Theoretical Chemistry, University of Stuttgart, 70049 Stuttgart, Germany

Cavity-controlled chemical reactions of ultracold atoms

References

[1] C. Junge, D. O’Shea, J. Volz, A. Rauschenbeutel, Phys. Rev. Lett. 110, 213604 (2013)

[2] P. Lodahl, S. Mahmoodian, S. Stobbe, A. Rauschenbeutel, P. Schneeweiss, J. Volz, H. Pichler, P. Zoller, Nature 541, 473–480, (2017)

[3] M. Scheucher, A. Hilico, E. Will, J. Volz, A. Rauschenbeutel, Science, 354, 6319, 1577-1580 (2016)

References

[1] A. Dombi, A. Vukics, P. Domokos , EPJD 69, 3 (2015)

[2] H. J. Carmichael, Phys. Rev. X 5, 031028 (2015)

[3] J. M. Fink, A. Dombi, A. Vukics, A. Wallraff, P. Domokos, Phys. Rev. X 7, 011012 (2017)

Non-equilibrium phase transitions ex-ist in damped-driven open quantum

systems, when the continuous tuning of an external parameter leads to a transi-tion between two robust steady states [1]. In second-order transitions this change is abrupt at a critical point, whereas in first-order transitions the two phases can co-exist in a critical hysteresis domain.

Interestingly, in an experiment carried out by Johannes Fink at the ETH Zürich, in the group of Andreas Wallraff, a very robust quantum bistability has been found for pumping the cavity at resonance, whereas the calculation presented for the JC model suggests that the waiting time to reach the excited attractor diverges close to resonance. The bistability in the JC model was found for a finite detuning from resonance.

When explaining these experimental re-sults, it is important to take into account a more realistic level scheme for the ar-tificial atom. Along with presenting our calculations, it will be shown how well the observations can be interpreted by means of a three-level scheme in a single-mode field model. By exploiting the additional tunability of parameters in the simulation, – inaccessible in a real experiment –, we could unambiguously demonstrate that the observed behavior results take place when the photon blockade of the driven cavity-atom system is broken by increas-ing the drive power [2]. The observed ex-perimental signature is a bimodal phase space distribution with varying weights controlled by the drive strength [3].

András Dombi1, J. M. Fink2, A. Vukics1, A. Wallraff3, P. Domokos1

1 Wigner Research Centre for Physics, H-1525 Budapest, P.O. Box 49., Hungary2 Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria3 Department of Physics, ETH Zürich, CH-8093 Zürich, Switzerland

Observation of the photon-blockade breakdown phase transition

Integrated optical circuits for informa-tion processing promise to outperform

their electronic counterparts in terms of bandwidth and energy consumption. However, such circuits require compo-nents that control the flow of light. Here, a particular important class are nonrecipro-cal devices.

Recently, we realized a quantum optical circulator. For this purpose, we strongly couple a single 85Rb atom to a special type of whispering-gallery-mode resona-tor - a so-called bottle microresonator [1] - in which photons exhibit a chiral nature: their polarization is inherently linked to their propagation direction [2]. Interfaced by two optical nanofibers, the

system forms a 4-port device. The chi-rality of the photons together with the atom exhibiting polarization-dependent transition strengths leads to a direction-dependent atom-photon interaction. As a consequence, we observe a nonrecipro-cal behaviour, where photons are directed from one to the adjacent fiber-port [3]. We also show that the internal quantum state of the atom controls the operation direc-tion of the circulator [3]. This working principle is compatible with preparing the circulator in a coherent superposition of its operational states. It thus may become a key element for routing and processing quantum information in scalable integrat-ed optical circuits.

M. Scheucher, A. Hilico, Elisa Will, L. Masters, J. Volz, and A. RauschenbeutelVienna Center for Quantum Science and Technology, Atominstitut, TU Wien, Austria

Quantum optical circulator controlled by a single chirally coupled atom

|f>

L

|e>

|g>

S+S

S+P

g g

inter-atomic distance

ener

gy

Figure 1. Our two-photon chemical reac-tion scheme for two Rb atoms: Shown are the potential energy curves and some bound states (blue). A laser L couples two unbound ground state atoms, denoted as |f>, to a bound excited molecular state |e> (photoassociation). The cavity (g) couples this state to a molecular ground state |g>. Alternatively, the molecule can also potentially decay to other states at rate 2γ.

References

[1] S. Ritter et al., Nature 484, 195 (2012)

[2] A. Reiserer, N. Kalb, G. Rempe, S. Rit-ter, Nature 508, 237 (2014)

[3] S. Welte, B. Hacker, S. Daiss, S. Ritter, G. Rempe, Phys. Rev. Lett. 118, 210503 (2017)

[4] L.-M. Duan, B. Wang, H. J. Kimble, Phys. Rev. A 72, 032333 (2005)

Optical high-finesse resonators pro-vide an interface between flying

photonic qubits and stationary matter qubits [1,2], which is the foundation of an extended quantum network for quantum communication and distributed quantum computing. To build a scalable network architecture, each node is required to hold several qubits [3] that are connected through quantum gate operations. We present our experiment where such a gate [4] is realized on two neutral 87Rubidium atoms trapped inside of a strongly cou-

pled optical resonator. The gate is itself mediated by one optical photon, travel-ling in the network channel of our reso-nator. This creates an interaction that is independent of the distance between the atoms. We demonstrate the functionality of our gate as a CNOT as well as an en-tangling operation on the two atoms. The mechanism offers the perspective of one-step many-atom gates or hybrid gates be-tween several atoms and a network pho-ton.

Bastian Hacker, S. Welte, S. Daiss, S. Ritter, and G. RempeMax-Planck-Institute of Quantum Optics, Hans-Kopfermann-Str. 1, 85748 Garching, Germany

Two-atom quantum gate using an optical resonator

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We show a systematic study of the impact of disorder on the optical

properties and intervalley scattering of atomically thin MoS2. Using a helium ion microscope (HIM) we induce defects in the crystal lattice. Optical analysis reveals significant shifts of both first order Raman modes E’ and A1 which are well explained by phonon confinement due to increasing disorder linking the ion dose to the inter-defect distance. Low-temperature (T=10K) confocal micro-photoluminescence (µ-PL) exhibits additional pronounced defect-re-lated luminescence that can be precisely tailored with the ion dose used for expo-sure. We attribute the observed lumines-cence to originate from chemisorbed at-oms/molecules at mono-sulfur vacancies in good agreement with DFT calculations. Quasi-resonant polarization resolved µ-PL measurements reveal a robust degree of circular polarization η ~ 85% for doses where ion-induced luminescence is ob-served. This observation is in good agree-ment with the occurrence of mono-sulfur vacancies that are not contributing to in-tervalley scattering due to their C3-sym-metry as recently theoretically reported [2]. Moreover, we will present preliminary

results on single defect luminescence in hBN-MoS2-hBN heterostructures [3], which resembles quantum dot-like emis-sion in as-exfoliated TMDCs.

Our results demonstrate the potential of helium ion microscopy applied to 2D lay-ered materials for modifying intrinsic op-tical properties and fundamental under-standing of disorder and its implication on the valley depolarization [4].

References

[1] Mignuzzi et al., Phys. Rev. B 91, 195411 (2015)

[2] Kaasbjerg et al., arXiv:1612.00469 (2016)

[3] Wierzbowski et al., arXiv:1705.00348 (2017)

[3] Klein et al., arXiv:1705.01375 (2017)

J. Klein1,2, A. Kuc3,4 ,A. Nolinder1, M. Altzschner1, J. Wierzbowski1, F. Sigger1, F. Kreupl5, J. J. Finley1,2, U. Wurstbauer1,2, A. W. Holleitner1,2 and Michael Kaniber1,2

1 Walter Schottky Institut und Physik Department, Technische Universität München, Am Coulombwall 4, 85748 Garching, Germany2 Nanosystems Initiative Munich (NIM), Schellingstr. 4, 80799 Munich, Germany3 Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, 04103 Leipzig, Germany4 Department of Physics & Earth Sciences, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany5 Department of Hybrid Electronic Systems, Technische Universität, Arcisstr. 21, 80333 Munich, Germany

References

[1] K.A. Fischer, L. Hanschke et al. Nature Physics doi:10.1038/nphys4052 (2017)

References


[2] J. A. Souza, E. Figueroa, H. Chibani, C. J. Villas-Boas, and G. Rempe, Phys. Rev. Lett. 111, 113602 (2013)

A strongly coupled cavity QED system shows anharmonicity in its energy

level structure that provides a platform to realize n-photon blockade [1]. By adding a classical beam that couples the excited state to another ground state a strongly coupled single atom cavity EIT system can be realized. The classical control beam provides freedom to control the quantum statistical property of the light emitted from the cavity [2]. Although the EIT states have narrow linewidth and lon-ger lifetime, its energy levels are equally spaced so that a resonant beam probing the system remains a coherent field. Here,

we show theoretically that by introducing a frequency detuning of the cavity, the harmonic ladder of EIT states is broken at the expense of mixing a small part of the excited atomic state into the dark states. Then, multi-photon blockade can be re-alized with these narrow states through atom driving. By adjusting the frequency of the control beam, the blockade photon number can be precisely tuned. Such a system provides a quantum device that al-lows to optically manipulate multi-photon quantum nonlinearities.

Gang Li1, 2, B. Wang1, K. N. Tolazzi1, T. Wilk1 and G. Rempe1

1 Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, D-85748 Garching, Germany2 State Key Laboratory of Quantum Optics and Quantum Optics Devices, and Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, China

Manipulation of quantum nonlinearities in single atom cavity EIT system

Helium ion modified luminescence and valley depolarization of atomically thin MoS2

Figure 1: (a) Schematic illustration of the helium ion exposed MoS2. (b) µ-PL (10 K) spectrum of MoS2 featuring the neutral exciton X and Trion T, low energy L-peak and the ion-induced LD peak.

In this work we propose a generalized Dicke model, consisting in a system of

artificial two levels dipoles capacitively coupled to a resonant circuit. The dipole-dipole interaction makes possible to reach the superradiance phase transition, which corresponds to a ferroelectric transition

for the polarization in the ground state. With the appropriate geometry it is pos-sible to switch from a ferroelectric ground state to an anti-ferroelectric one, which correspond to the so called lightmatter decoupling phase. For a finite system it is of particularly interested the border

region between the superradiant and the light-matter decoupling phases. Indeed here quantum fluctuations are prominent, with possible observations of squeezing in the ground state magnetic flux of the circuit resonator.

Daniele De BernardisTU Vienna, Austria

Dipolar systems in the ultra strong coupling regime

We demonstrate the generation of two-photon bundles from a single

quantum two-level transition in a semi-conductor quantum dots [1]. Quantum two-level systems in the solid state are poised to serve the pivotal role of an on-demand single-photon source by convert-ing laser pulses with Poissonian counting statistics to single photons. More recently, multi-photon quantum state generators have engendered strong interest as re-placements for the single-photon source in many quantum applications. Here we investigate theoretically and verify experi-mentally that the same two-level system that has long been studied for single-pho-ton generation can surprisingly operate in a two-photon bundling regime.

For on demand single-photon generation, the two-level system is typically excited with a resonant pulse of area pi. This pre-pares the two-level system in its excited state from where it spontaneously emits a single photon. In contrast, when excit-ing the system with a pulse of area 2pi, the system is expected to be returned to the ground state. However, if the ratio of pulse length to excited state lifetime is fi-nite, photon emission during the presence of the laser pulse is possible. This is most likely to happen when the system is in its excited state - after an area of pi has been absorbed. If such an emission occurs, the Rabi oscillation is restarted with a pulse area of pi remaining in the pulse which re-excites the system and leads to the emis-sion of a second photon within the excited state lifetime.

Lukas Hanschke1, K. A. Fischer2, J. Wierzbowski1, T. Simmet1, C. Dory2, J. J. Finley1, J. Vuckovic2 and K. Müller1 Walter Schottky Institut and Physik Department, Technische Universität München, 85748 Garching, Germany2 E. L. Ginzton Laboratory, Stanford University, Stanford, California 94305, USA

Two-photon bundles from a single two-level system

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References

[1] T. Nieddu et al. J. Opt. 18, 053001 (2016)

[2] R. Kumar et al. Phys. Rev. A 91, 053842 (2015)

[3] R. Kumar et al. New J. Phys. 17, 123012 (2015)

[4] C. Sayrin et al. Optica 2, 353 (2015)

[5] B. Gouraud et al. Phys. Rev. Lett. 114, 180503 (2015)

[6] S. Kato et al. Phys. Rev. Lett. 115, 093603 (2015)

[7] F. Le Kien et al. arxiv.org/abs/1703.00109 (2015)

Optical nanofibers with sub-wave-length diameter have been of great

interest for research in quantum optics in recent years [1]. The tight confinement of the guided light and the highintensity field along the fiber waist are used to establish an interface for studying the interaction between light and atomic ensembles at ultralow-power levels [2,3] and for fewer atoms [4,5]. Strong coupling between single atoms and single photons can also be realized by combining a nanofiber with FBG mirrors [6]. However, so far most ex-periments on atom-light interactions in an optical nanofiber are based on the funda-mental guided mode of the optical nano-fiber. Compared with this mode, higher-

order modes (HOM) have a stronger evanescent field around the fiber waist [7] to further enhance the atom-photon in-teraction and may carry orbital angular momentum (OAM). Here, we successfully excite pure or combination eigenmodes of the LP11 group of the optical nanofiber by carefully controlling the polarization and profile of the input beam. The interaction strength for different modes can be ob-tained by measuring the atomic absorp-tion spectra of the guided resonant beam. This make a first step towards thetransfer of orbital angular momentum (OAM) and the implementation of all-fibered high-dimensional optical memories.

Jinjin Du, T. Nieddu, and S. N. ChormaicLight-Matter Interactions Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Okinawa 904-0495, Japan

Atom-light interactions in a few-mode optical nanofiber

References

[1] M. Jerger et al., arXiv:1706.05829 (2017)

In experiments that require fast elec-trical control pulses, it is often crucial

that the signal reaching the sample is a faithful reproduction of the intended sig-nal. For highest precision, the frequency-dependent transmission coefficient of the control line must be taken into account. When both ends of the line are accessi-ble, the transmission coefficient is read-ily measured with a network analyzer, but when one end is inside a cryostat or signal transmission on the sample is to be included, that can be challenging. We have developed a method for the in-situ characterization of the response of a cryogenic microwave input line with the

aid of a superconducting qubit. By peri-odically modulating the energy level split-ting of the qubit, we determine the am-plitude and phase of transmission of the line controlling the level splitting from DC to 100 s of megahertz at millikelvin tem-peratures. This can be directly applied to improve the fidelity of several protocols, most notably controlled phase gates be-tween two superconducting quantum bits using magnetic flux frequency control. These gates are the most common way to generate two-qubit operations in super-conducting quantum processors and their fidelities rely on frequency control on a nanosecond time scale.

Markus Jerger, Z. E. Vasselin and A. FedorovARC Centre of Excellence for Engineered Quantum Systems, The University of Queensland, Brisbane, Queensland, AustraliaSchool of Mathematics and Physics, University of Queensland, Brisbane, Queensland, Australia

In situ characterization of qubit control lines: a qubit as a vector network analyzer

References

[1] C. Junge et al. Phys. Rev. Lett. 110, 213604 (2013)

[2] I. Shomroni et al. Science 345, 903 (2014)

[3] M. Scheucher et al. Science 354, 1577 (2016)

[4] J. D. Thompson et al. Science 340, 1202 (2013)

Whispering-gallery-mode (WGM) resonators guide light by total in-

ternal reflection and provide ultra-high optical quality factors in combination with a small optical mode volume. Coupling a single atom to the evanescent field of a WGM microresonator thus allows one to reach the strong coupling regime [1]. Furthermore, such resonators provide chiral light-matter coupling which can be employed for realising novel quantum protocols [2] as well as nonreciprocal quantum devices [3]. However, trapping atoms in the evanescent field of such res-onators has not yet been demonstrated, which severely limits the atom-resona-tor interaction time. We aim to trap and cool single 85Rb atoms in the vicinity of a bottle-microresonator (BMR) - a highly

prolate type of WGM resonator. A stand-ing wave optical dipole trap is created by retroreflecting a tightly focussed beam on the BMR surface (method similar to [4]). Due to trap-induced position depen-dent light shifts, the trap is alternatingly pulsed with a cooling laser faster than the trap frequencies to allow for Doppler cool-ing of the atomic motion while the atom is held in the trapping potential. In order to load atoms into the trap, we employ an FPGA-based electronics which allows us to react in 150 ns to an atom arriving in the resonator field and thus to switch on the dipole trap. We will present the first characterisations of our scheme.

Luke Masters, E. Will, M. Scheucher, A. Hilico, J. Volz, and A. RauschenbeutelVienna Centre for Quantum Science and Technology, Atominstitut, TU Wien, Vienna, Austria

Towards the realisation of an atom trap in the evanescent field of a microresonator

References

[1] K. Mak et al. Phys. Rev. Lett. 105, 136805 (2010)

[2] K. Huang et al. Nat. Photon 8, 244 (2014)

[3] A. Branny et al. Appl. Phys. Lett. 108, 142101 (2016)

[4] M. Blauth et al. 2D Mater. 4, 21011 (2017)

Atomically thin, two-dimensional semi-conductors have recently attracted

strong interest, both in the fields of nano-optics and nano-electronics [1]. Combin-ing these materials with nano-plasmonic waveguides opens the way to build inte-grable plasmonic light sources [2] and detectors with subwavelength footprints. In this contribution we present numeri-cal simulations and experimental studies of the coupling of monolayer MoSe2 crys-tals to proximal plasmonic waveguides. Detailed numerical studies on plasmonic waveguides demonstrate the presence of guided plasmonic modes confined within nanometer regions at the surface of the waveguides, yielding a transverse mode volume of ~ 0.02 λ2. Low temperature con-focal spectroscopy reveals the appearance of emission between 1.55 eV and 1.61 eV, redshifted from the MoSe2 exciton and trion emission [3]. We find degrees of po-larization of up to 40%, which are in good

agreement with spontaneous emission calculations that indicate radiation from the MoSe2 into the supported plasmonic modes. As evidence for coupling of the emission into these modes, we present optical propagation length measurements revealing LSPP= (380 ± 60)nm, thereby, proving the plasmonic character of the observed luminescence [4]. By electrically contacting the plasmonic waveguides we perform photocurrent measurements on the MoSe2 - plasmonic hybrid system. Ex-citation energy dependence of the photo-current show peaks at 1.67 eV and 1.85 eV corresponding to the A and B exciton resonance, respectively. We further show that excitation power density dependent photocurrent exhibits pronounced non-linearities for extraction fields exceeding 100 kV/cm. This could be exploited in fu-ture ultra-fast pump-probe spectroscopy, yielding new insight into the photocurrent dynamics of this hybrid system.

Mäx Blauth, G. Mélen, M. Prechtl, O. Hartwig, J. Harms, J. J. Finley, and M. KaniberWalter Schottky Institut and Physik Department, Technische Universität München, Am Coulombwall 4, 85748 Garching, Germany

Enhanced optical activity of atomically thin MoSe2 proximal to nanoscale plasmonic slot-waveguides

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Solid-state superconducting circuit qubits are one of the most promis-

ing platforms for the implementation of fault-tolerant quantum computers owing to their potential for scalability [1]. Cur-rently, a feasible scheme to generate the signals to control/readout these qubits is via commercial-off-the-shelf (COTS) electronics [1,2], operating at the room-temperature. As the number of qubits on a single device is rapidly proliferating, the usage of COTS becomes prohibitive from the cost-per-qubit and system complexity point of view, hindering the scalability. An active area of research is, therefore, to replace COTS with more customized plat-forms [3,4] or even microwave/RF inte-grated circuits (RFIC), which can lead to a significant reduction of form factor, power consumption, and system cost/complex-ity. This also unfolds the possibility of op-erating them at even the cryogenic tem-peratures, offering numerous advantages by circumventing the excessive delays in the measurement setup (e.g., delay of cables and digital controller [2]). One of the caveats of a Cryo-RFIC, as opposed to COTS electronics, can be exacerbated noise/accuracy performance, which arises due to the restricted power consumption

budgets at cryogenic temperatures. It is, therefore, crucial to identify the trade-offs in the system-level design of the electron-ics and its impact on the qubit fidelity, to be able to implement power-efficient Cryo-RFICs. In this work, we focus on the readout electronics chain of super-conducting qubits within the circuit QED framework. We analyze a demonstrative case of multi-qubit single-shot, high-fidel-ity readout, featuring frequency domain multiplexing (FDM). We attempt to model and articulate the impact of the interro-gating (probe) microwave-pulse source imperfections (amplitude, frequency, and phase errors and noise, spurious tones etc.) as well as the homodyne demodula-tion chain design requirements (RF ampli-fiers gain/noise distribution, ADC speed/resolution etc.).

Acknowledgment: The authors would like to thank Intel Corp. for funding.

Milad Mehrpoo1, F. Sebastiano1, E. Charbon1,2, M. Babaie1

1 Department of Quantum Engineering, Delft University of Technology, Delft, the Netherlands 2 Intel, Hillsboro, Oregon

References

[1] J. Gambetta et al. npj Quantum Infor-mation 3, 2 (2017)

[2] D. Ristè et al. Phys. Rev. Lett. 109, 240502 (2012)

[3] C. Ryan et al. arXiv:1704.08314 (2017)

[4] H. Homulle et al. Rev. of Sci. Inst. 88, 045103 (2017)

Design considerations of cryo-RFICs for superconducting qubits readout

While photons are ideal for the trans-mission of quantum states, they re-

quire dedicated memories for long-term storage. The challenge for such a photon-ic quantum memory is the combination of an efficient light-matter interface with a low-decoherence encoding.

To increase the time before the quantum state is lost, a thorough analysis of the

relevant decoherence mechanisms is in-dispensable. Our optical quantum mem-ory consists of a single rubidium atom trapped in a two dimensional optical lat-tice in a high-finesse Fabry-Perot optical resonator. The qubit is initially stored in a superposition of Zeeman states, making magnetic field fluctuations the dominant source of decoherence. The impact to this type of noise is greatly reduced by trans-

ferring the qubit into a subspace less sus-ceptible to magnetic field fluctuations. In this configuration, the achievable coher-ence times are no longer limited by those fluctuations, but decoherence mecha-nisms induced by the trapping beams pose a new limit. We will discuss the ori-gin and magnitude of the relevant effects and strategies for possible resolutions.

Matthias Körber, O. Morin, S. Langenfeld, A. Neuzner, S. Ritter, and G. RempeMax-Planck-Institut für Quantenoptik, Hans-Kopfermann-Strasse 1, 85748 Garching, Germany

Analysis of decoherence mechanisms in a single-atom quantum memory

Plasmonic nano-particle dimers are well known to create strongly en-

hanced electromagnetic fields, localized within nanometre-sized optical volumes in the feed-gap separating the compo-nent particles. Here, we experimentally probe the response of near surface opti-cally active quantum dots (QDs) coupled to lithographically defined bowtie (BT) nano-antennas. Numerical simulations indicate that such plasmonic structures enhance the electromagnetic intensity in the feed-gap up to ≥ 103 × compared to the incident field. We fabricated Au BTs on GaAs substrates with triangle sizes of 60 - 200 nm and feed gaps of 5 - 50 nm [1, 2]. Using non-linear optical spectroscopy, we directly measure the field enhance-ment in the hot-spot of the BT antenna to be > 2000 × for BTs with an Au-thickness of 35 nm, triangle size of 140 nm and feedgap of 10 nm [3].

Furthermore, we probe the light-matter-coupling between the plasmonic field con-centrated in the BT feed gap and individ-ual near-surface self-assembled InGaAs QDs [4]. We find an unambiguous correla-tion between the QDs’ emission intensity and their location with respect to the BTs. We observe an increase of the QD pho-toluminescence intensity up to 16 × for QDs coupled to antennas. Polarisation-re-solved spectroscopy reveals strongly lin-early polarized emission from individual QDs with a degree of polarization η > 85%. By performing time-resolved measure-ments this enhancement is attributed to

an increased spontaneous emission rate, with measured Purcell Factors > 3.4 × (Fig. 1). Finally, we will present first re-sults from single photon correlation spec-troscopy, clearly demonstrating non-clas-sical light generation.

Our findings pave the way towards new semiconductor-plasmonic hybrid systems for applications in sensing, non-linear op-tics and quantum information science.

References

[1] K. Schraml et al. Phys. Rev. B 90, 035435(2014)

[2] M. Kaniber et al. Sci. Rep. 6, 23203(2016)

[3] K. Schraml et al. Optica 3, 1453(2016)

[4] A. A. Lyamkina et al. Opt. Exp. 24, 28936(2016)

A. Regler, A. A. Lyamkina, Anna Nolinder, A. K. Bakarov, A. I. Toropov, S. P. Moshchenko, K. Müller, J. Vuckovic, J.J. Finley and M. KaniberWalter Schottky Institut und Physik Department, Technische Universität München, Am Coulombwall 4, 85748 Garching, GermanyTUM Institute of Advanced Study, Lichtenbergstraße 2a, 85748 Garching, GermanyA. V. Rzhanov Institute of Semiconductor Physics SB RAS, Pr. Lavrentieva 13, 630090 Novosibirsk, RussiaNovosibirsk State University, Pirogova 2, 630090 Novosibirsk, RussiaStanford University, E. L. Ginzton Laboratory, 348 Via Pueblo Mall, Stanford, California 94305 United States

Enhanced spontaneous emission from quantum dots coupled to metal nano-antennas

Figure 1: Time-resolved data of an antenna-coupled (red) and reference (blue) quantum dot. Inset: SEM image of bowtie nanoantenna.

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Polarization-entangled photon pairs play a key role in scalable quantum

communication applications. They en-able secure quantum key distribution [1], robust qubit transfer via teleportation [2] and can be used to distribute entangle-ment between separated computation nodes, rendering even a “quantum inter-net” possible [3].

However, deterministic sources of highly entangled photon pairs challenge the community for already more than two decades. Semiconductor quantum dots are among the leading candidates for this task, offering pure single photon pair emission with high internal quantum ef-ficiency, outperforming probabilistic sources based on spontaneous parametric down-conversion. Despite various inves-tigated material systems [4,5,6,7], most quantum dot species suffer from extreme-

ly low yield, low degree of entanglement and poor wavelength control, blocking the way for scalable applications.

Here, we show that with an emerging family of GaAs/AlGaAs quantum dots grown by droplet etching and nanohole infilling, it is possible to obtain a large solid-state emitter ensemble of highly en-tangled photons pairs on a wafer - without any post-growth tuning [8]. Under pulsed resonant two-photon excitation, all mea-sured quantum dots emit single pairs of entangled photons with ultra-high purity, high degree of entanglement and ultra-narrow wavelength distribution at rubid-ium transitions. Therefore, this material system is an attractive candidate for the realization of a solid-state quantum re-peater - among many other key enabling quantum photonic elements.

References

[1] A. K. Ekert, Phys. Rev. Lett. 67, 661 (1991)

[2] C.H. Bennett et al., Phys. Rev. Lett. 70, 1895 (1993)

[3] H. J. Kimble, Nature 453, 1023-1030 (2008)

[4] G. Juska et al., Nat. Photonics 7, 527 (2013)

[5] M. Müller et al., Nat. Photonics 8, 224-228 (2014)

[6] M. A. Versteegh et al., Nat. Commun. 5, 6298 (2014)

[7] T. Kuroda et al., Phys. Rev. B 88, 031306 (2013)

[8] R. Keil and M. Zopf et al., Nat. Com-mun. 8, 15501 (2017)

Robert Keil1, M. Zopf1, Y. Chen1, B. Höfer1, J. Zhang1, F. Ding1,2 and O. G. Schmidt1,3

1 Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstraße 20, 01069 Dresden, Germany2 Institut für Festkörperphysik, Leibniz Universität Hannover, Appelstrasse 2, 30167 Hannover, Germany3 Material Systems for Nanoelectronics, TU Chemnitz, 09107 Chemnitz, Germany

Solid-state ensemble of highly entangled photon sources at rubidium atomic transitions

References

[1] K. G. Fedorov, et al., Phys. Rev. Lett. 117, 020502 (2016)

[2] K. G. Fedorov, et al., arXiv:1703.05138 (2017)

[3] J. Goetz, et al., Phys. Rev. Lett. 118, 103602 (2017)

Stefan Pogorzalek1,2, K. G. Fedorov1,2, S. Trattnig1,2, B. Ghaffari1,2, P. Eder1,2,3, M. Fischer1,2,3, J. Goetz1,2, E. Xie1,2,3, A. Marx1, F. Deppe1,2,3 and R. Gross1,2,3

1 Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany2 Physik-Department, TU München, 85748 Garching, Germany3 Nanosystems Initiative Munich (NIM), 80799 München, Germany

Josephson parametric amplifiers (JPAs) can be employed for the generation of

itinerant quantum signals in the form of propagating two-mode squeezed (TMS) states [1-2], which are essential for quan-tum communication protocols. Further applications of TMS states include quan-tum information processing with continu-ous variables, or novel ideas of building quantum annealing networks based on

JPAs. In our experiments, we employ two flux-driven JPAs [3] at the inputs of an en-tangling hybrid ring in order to generate two-mode squeezing between the hybrid ring outputs. We perform tomography of the resulting TMS states and experimen-tally investigate the robustness of non-classical correlations, such as quantum entanglement and quantum discord, to noise and finite-time delays.

Quantum correlations in propagating two-mode squeezed microwave states

In nano-electromechanics, quantum mechanical phenomena can be stud-

ied in the literal sense. For the prepara-tion of mechanical (phonon) Fock states, the integration of a sufficiently nonlinear circuit element is of key importance. One possible realization is to combine the field of superconducting circuit QED with su-perconducting nano-electromechanical devices.

Here, we present a hybrid system consist-ing of a superconducting coplanar micro-wave resonator acting as a bus between

a nanomechanical string resonator and a transmon qubit. The latter is, just as the rest of the circuit, fabricated using alumi-num technology and acts as nonlinear el-ement. We present the device layout and characterize the device parameters using continuous wave spectroscopy of both the transmon qubit and the nano-mechanical string resonator. Additionally, we investi-gate the photon number of the microwave resonator via two complementary ap-proaches: First we use the ac-Stark shift of the coupled qubit-microwave resonator system. Second we use electromechani-

cally induced absorption, an interfer-ence effect, present in electromechanical devices. Although these two approaches probe the photon number in comple-mentary regimes differing by ten orders of magnitude, they exhibit quantitative agreement. In summary, we present suc-cessful integration of a nanostring in mi-crowave resonators in combination with a transmon qubit and show successful ex-periments on interfacing circuit QED and nanomechanical strings.

Philip Schmidt1,2,3, D. Schwienbacher1,2,3, M. Pernpeintner1,2,3, F. Wulschner1,2,3,4, L. Rosenzweig1,2, C. Utschick1,2, F. Deppe1,2, A. Marx1, R. Gross1,2,3 and H. Huebl1,2,3

1 Walther-Meißner-Insitut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany2 Physik-Departement, Technische Universität München, 85748 Garching, Germany3 Nanosystems Initiative Munich, Schellingstraße 4, 80799 München, Germany4 present address: Universität Wien, Boltzmanngasse 5, 1090 Wien, Austria

References

[1] M. Russ and G. Burkard, Phys. Rev. B 92, 205412 (2015)

[2] M. Russ, F. Ginzel, and G. Burkard, Phys. Rev. B 94, 165411 (2016)

[3] M. Russ, G. Burkard (review article), aXiv: 1611.09106 (2016) (accepted for IOP JPCM)

[4] G. Burkard, J.R. Petta, Phys. Rev. B 94, 195305 (2016)

[5] X. Mi, C.G. Péterfalvi, G. Burkard, J.R. Petta, arXiv: 1704.06312 (2017)

Semiconductor qubit cavity hybrid sys-tems are currently under intense in-

vestigation due to its application in long-distance entanglement protocols [1,2,3] and fast quantum-state read-out schemes [4,5]. We investigate the behavior of qu-bits consisting of three or more electron spins in semiconductor triple quantum dots (TQDs) which are coupled to a mi-crowave cavity via their electric dipole moment. Unlike single-spin systems mul-tiple-spin systems possess a dipole mo-ment from charge hybridization which is electrically tunable while still possessing the longevity of single-spin qubits.

Our model includes both longitudinally and transversally embedded qubits within a cavity yielding a qubit-cavity coupling to two independent TQD detuning param-eters. These parameters can be controlled in experiments by gate voltages applied

to the quantum dot structures. By varying the detuning parameters, one can switch the qubit type by changing the electron occupancy in each quantum dot as well as their degree of hybridization.

In a semi-microscopic approach, we cal-culate the transition dipole matrix ele-ments of the qubit-cavity interaction. From this we can determine the qubit-cavity coupling strength needed for en-tangling two-qubit gates and dispersive read-out. We investigate both geometries and a compare the two with and without the influence of charge noise. Both geom-etries show a switchable qubit-resonator coupling depending on the detuning pa-rameters. As a final result, the require-ments for the vacuum coupling strength and quality factor of the cavity are includ-ed in our results.

Maximilian Russ and G. BurkardDepartment of Physics, University of Konstanz, D-78457 Konstanz

Coupling multiple-spin qubits via a microwave resonator

Transmon qubits meet cavity electromechanics

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We demonstrate an entirely new method to probe quantum mea-

surement phenomena in semiconductor quantum dot (QD) spin qubits [1]. In ad-dition to providing direct evidence for the quantum nature of solid state qubits, we show that our method has practical im-portance since it provides a completely alternative route for measuring ensemble and quantum dephasing times, T2* and T2, using only repeated projective measure-ments and without the need for coherent spin control.

Our approach is based on measuring time-correlators of a spin qubit in an opti-

cally active QD beyond the second order. We utilize a quantum dot spin-storage structure to initialize a single electron spin in a quantum dot subject to a mag-netic field applied in Voigt geometry and perform repeated projective measure-ments of the spin at times t1 and t2. This measurement is repeated, corresponding to ensemble averaging, and the resulting third-order time correlations reveal rich physics: For times t1 or t2 <T2* Larmor pre-cession is observed which reveals the en-semble dephasing time T2*. Importantly, even though the time-correlators were ob-tained through averaging many measure-ments for times t1 and t2 > T2* oscillations

are observed that decay with the dephas-ing time T2 and allow its determination even without the need for coherent spin control. Finally, combining the third-or-der time correlator with the second-order time correlator allows to demonstrate a violation of Leggett-Garg type inequalities for certain times providing clear evidence for the quantum nature of the quantum dot spin.

Tobias Simmet1, K. Müller1, A. Bechtold1, F. Li2, N. Sinitsyn2, J. J. Finley1

1 Walter Schottky Institut and Physik Department, Technische Universität München, 85748 Garching, Germany2 Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545 USA

References

[1] A. Bechtold et al. Phys. Rev. Lett. 117, 027402 (2016)

Optically probing spin qubit coherence without coherent control

References

[1] T. Bagci et al., Nature 507, 81–85 (2014)

[2] R. W. Andrews et al., Nat. Phys. 10, 321–326 (2014)

[3] J. Bochmann et al., Nat. Phys. 9, 712–716 (2013)

Superconducting microwave circuits are very promising candidates for

implementing efficient quantum infor-mation processing. In contrast, the ideal platform for long-distance communica-tion is provided by photons propagating in optical fibers due to the ultra-low loss. Consequently, a key ingredient to estab-lish a long distance quantum network is a high efficiency converter of photons between microwave frequencies and op-tical wavelengths. There are first demon-strations of microwave-optical conversion using mirror-membrane systems [1,2] and piezoelectric optomechanical crystals [3] reaching conversion efficiencies as high as 10%. Our goal is to implement an in-tegrated on-chip transducer that allows conversion between microwave and opti-cal photons with high efficiency and low added noise at millikelvin temperatures. In our approach we use a mechanical res-

onance to couple a photonic crystal cavity to a mechanically compliant capacitor of a superconducting microwave circuit on an SOI platform which is fully compatible with superconducting qubits. To reach an efficiency close to unity, a sufficiently high electromechanical coupling and a mechanical frequency exceeding the opti-cal linewidth is required. We will present our progress in the implementation of an on-chip integrated microwave-to-optics transducer.

Matthias Wulf, G. Arnold, D. Swen, A. Rueda, S. Barzanjeh, M. Peruzzo, and J. M. FinkInstitute of Science and Technology Austria, 3400 Klosterneuburg, Austria

On-chip transduction of microwave and optical signals using nanomechanical resonators

Figure: FEM simulation of the mechanical resonance of the designed prototype.

References

[1] C. Monroe et al., Phys. Rev. A 89, 022317 (2014)

[2] www.femtoprint.ch

Atomic ions trapped in radio frequency traps and cooled by laser light are a

leading candidate for a quantum informa-tion processor. Scaling such a system by controlling a large number of ions con-fined in a single trap presents immense technical challenges. One possibility would be to link a large number of well controlled modular ion trap processors through optical interconnects to form a scalable ion trap quantum architecture [1]. I will present work towards an ion trap that could serve as such a module. The trap will be build using fused silica

wafers etched following laser ablation [2], allowing us to realize arbitrary electrode configurations and shapes as well as to provide optical access for a high-finesse cavity while shielding the ions from pos-sible effects of dielectric mirror charging. Furthermore it allows to provide precise and foolproof relative alignment of the trap wafers. An initial run will use a fibre cavity at 854 nm, with a length of 350 µm and ROC of 250 μm to target high ion-pho-ton coupling strength.

Simon Ragg, K. Theophilo, and J. P. HomeTrapped Ion Quantum Information Group, ETH Zurich, 8093 Zurich, Switzerland

Modular segmented ion trap with an integrated optical cavityP32

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The realization of scalable quantum networks requires efficient and ro-

bust light-matter interfaces. In this re-gard, solid-state systems such as color centers in diamond are strong candidates towards this goal as they possess optical transitions (source for flying qubits) to-gether with optically accessible spins (i.e. stationary qubit). However, it has been challenging to obtain a solid-state emitter to simultaneously offer excellent optical properties and long spin coherence times. Silicon-vacancy (SiV) center in diamond is a promising candidate for having a high quality optical transition and an optically accessible spin [1,2]. However, the spin coherence time of the SiV suffers from the resonant phonons in the environment that lead to spin-flips and loss of coherence [3]. In this work [4], by using a nano-electromechanical system, we control the electronic structure of the SiV by applying

a controlled strain. This capability allows us to demonstrate a wavelength tunability of more than 10 times the typical inhomo-geneous broadening in the system. Fur-thermore, coherent population trapping (CPT) measurements reveal that (Figure 1) by tuning the ground state splitting by means of strain, effects of phonons can be reduced which in the end results in in-creased spin coherence times.

References

[1] C. Hepp et al., Phys. Rev. Lett. 112, 036405 (2014)

[2] T. Müller et al., Nat. Commun. 5, 3328 (2014)

[3] K. D. Jahnke et al., New J. Phys. 17, 043011 (2015)

[4] Y-I. Sohn, S. Meesala, B. Pingault et al., arXiv: 1706.03881

Y-I. Sohn1, S. Meesala1, B. Pingault2, H. A. Atikian1, J. Holzgrafe1,2, Mustafa Gündoğan2, C. Stavrakas2, M. J. Stanley2, A. Sipahigil3, J. Choi1,3, M .Zhang1, J. L. Pacheco4, J. Abraham4, E. Bielejec4, M. D. Lukin3, M. Atatüre2, M. Loncar1

1 John A. Paulson School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, MA 02138, USA2 Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, UK3 Department of Physics, Harvard University, 17 Oxford Street, Cambridge, MA 02138, USA4 Sandia National Laboratories, Albuquerque, NM 87185, USA

Engineering a diamond spin-qubit with a nano-electro-mechanical system

Figure 1: CPT linewidth as a function of ground state splitting.

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In a quantum network, optical resona-tors provide an ideal platform for the

creation of interactions between matter qubits [1]. This is achieved by exchange of photons between the resonator-based network nodes, and in this way enables the distribution of quantum states and the generation of remote entanglement. Here we will show how photons can also be used to generate local entanglement be-tween matter qubits in the same network node [2].

Such entangled states are indispensable as a resource in a plethora of quantum communication protocols. We will give an overview of the necessary experimental toolbox for an implementation with neu-tral atoms, that are are strongly coupled to a high-finesse optical cavity. Two en-

tangling protocols allowing for the gen-eration of all four two-atom Bell states will be presented. The protocols rely on the reflection of coherent light from the atom-cavity system. Detection of a polari-sation flip heralds the entanglement and postselection allows us to remove parts of the combined two-atom state, a method called carving [3,4]. We achieve fidelities with the ideal Bell states of about 90%. Our entanglement mechanism does not depend on the interatomic distance and can be applied to any matter qubit with a closed optical transition. Furthermore, no individual addressing of the atoms is re-quired. One of the potential applications of the presented entangling scheme is the entanglement swapping procedure in a quantum repeater based on neutral atoms in optical resonators [5].

Stephan Welte, B. Hacker, S. Daiss, L. Li, S. Ritter and G. RempeMax Planck Institute of Quantum Optics, Hans-Kopfermann-Str. 1, 85748 Garching, Germany

References

[1] H.J. Kimble, Nature 453, 1023 (2008)

[2] A. Sørensen, K. Mølmer, Phys. Rev. Lett. 90, 127903 (2003)

[3] W. Chen, J. Hu, Y. Duan, B. Braver-man, H. Zhang, V. Vuletić, Phys. Rev. Lett. 115, 250502 (2015)

[4] S. Welte, B. Hacker, S. Daiss, S. Ritter, G. Rempe, Phys. Rev. Lett. 118, 210503 (2017)

[5] M. Uphoff, M. Brekenfeld, G. Rempe, S. Ritter, Appl. Phys. B 122, 46 (2016)

Generation of atomic Bell states in a cavity via quantum state carving

References

[1] Z-L. Xiang et al., Review of Modern Physics 85, 623 (2013)

[2] J. T. Muhonen et al., Nature Nano-technology 9, 986 (2014)

[3] A. M. Tyryshkin et al., Nature Materi-als 11, 143 (2012)

[4] K. Saeedi et al., Science 342, 830 (2013)

[5] G. Feher et al., Physical Review 100, 1784 (1955)

Stefan Weichselbaumer1,2, P. Natzkin1,2, C. W. Zollitsch1,2, S. T. B. Goennenwein1,2,3, M. S. Brandt2,4, R. Gross1,2,5, H. Huebl1,2,5

1 Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, Garching2 Physik-Department, Technische Universität München, Garching3 Institut für Festkörperphysik, Technische Universität Dresden, Dresden4 Walter Schottky Institut, Technische Universität München, Garching5 Nanosystems Initiative Munich, Munich

Spin ensembles in solids are promising candidates to realize quantum infor-

mation storage and processing by com-bining them with other systems to form hybrid quantum systems [1]. Phosphorus donors in isotopically purified 28Si are of particular interest, as they exhibit elec-tron and nuclear spin coherence times ex-ceeding 0.5 s [2, 3] and 39 min [4]. These values have been reported for extremely diluted donor ensembles. However, for two-donor qubit gates the donors need to be in close proximity to enable spin-spin coupling warranting the investigation of the coherence time under this circum-stances. At high doping concentrations, the phosphorus donors form exchange-coupled donor pairs [5], which allow to study this situation.

We perform pulsed electron spin reso-nance using a superconducting micro-wave resonator to study the coherence properties at Millikelvin temperatures. We perform single-shot Hahn echo ex-periments to measure the spin coherence time T2 of these phosphorus dimers. We find that the T2 time remains constant at temperatures below 250 mK, indicat-ing that the exchange coupling between phosphorus donors does not lead to ad-ditional dephasing.

This work is supported by the DFG via SPP 1601 (HU1861/2-1).

Investigation of coherence times of phosphorus dimers in 28Si at millikelvin temperatures

References

[1] K. M. Birnbaum et al., Nature 436, 87 (2005)


A single two-level atom strongly cou-pled to a light field inside a high-

finesse optical resonator is a paradigm of fundamental matter-light interaction. The coupled system exhibits a genuine quantum nonlinearity that is apparent in the new set of eigenstates, which form a ladder of doublets with a splitting increas-ing with the square root of the number of excitations. This nonlinearity is the origin of many quantum effects, one of which is single-photon blockade [1]. Here, we ex-tend the principle of single-photon block-ade to two photons: driven on resonance with the second pair of dressed states, the coupled atom-cavity system stores only up to two excitations. As a signature, the light emitted from the cavity exhibits

three-photon antibunching with simul-taneous two-photon bunching [2]. The two-photon blockade is only observed for driving of the system via the atom, while cavity driving results in strong two- and three-photon bunching. This can be un-derstood intuitively: while a two-level atom can only add excitations to the sys-tem one-by-one, the cavity is not restrict-ed in excitation number. The latter leads to bosonic enhancement which causes the transition strengths between the dressed states to increase with the number of ex-citations in the system while they remain constant for atom driving. This result is a significant step towards multi-photon quantum nonlinear optics and the realiza-tion of n-photon sources.

Tatjana Wilk, C. Hamsen, N. Tolazzi and G. Rempe Max Planck Institute of Quantum Optics, Hans-Kopfermann-Str. 1, 85748 Garching, Germany

References

[1] T. Nieddu et al., J. Opt. 18 053001 (2016)

[2]. S. M. Skoff et al., arxiv.org/abs/1604.04259 (2016)

[3]. A. W. Schell et al., Sci. Rep. 5, 9619 (2015)

[4]. K. P. Nayak et al., Opt. Lett. 39, 232 (2014)

[5]. K. P. Nayak et al., Opt. Express 19, 14040 (2011)

[6]. W Li et al., Appl. Phys. Lett. 110, 253102 (2017)

Recently optical nanofibers (ONF) have been used for investigating

light-matter interactions at the quantum level. These subwavelength optical fibers can be interfaced with various quantum emitters including neutral atoms [1], mol-ecules [2] and semiconductor quantum dots [3]. Optical nanofiber-based cavities enhance the interactions and can be made of fiber Bragg gratings (FBG) or photonic crystal structures. These kinds of cavi-ties could provide a platform for tailoring the interactions between light and matter and may have an application in quantum information processing. Here, we pres-ent an optical nanofiber-based cavity by combining a 1-D photonic crystal [4] and

Bragg grating structures [5]. The cavity morphology comprises a periodic, triplex air-cube introduced at the waist of the nanofiber [6]. The cavity has been theo-retically characterized using finite-differ-ence time-domain simulations to obtain the reflection and transmission spectra. We have also experimentally measured the transmission spectra, and a Q-factor of ~780 for a very short periodic struc-ture has been observed. The structure provides strong confinement of the cavity field, and it has demonstrable potential for realizing strong coupling cavity QED with single atoms and photons.

Wenfang Li, J. Du, V. G. Truong, S. N. ChormaicLight-Matter Interactions Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Okinawa 904-0495, Japan

Optical nanofiber-based cavity induced by periodic air-nanohole arrays

Two-photon blockade in an atom-driven cavity QED system

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References

[1] N. Gisin et al., Rev. Mod. Phys. 74, 145 (2002)

[2] A. Muller et al., Phys. Rev. Lett. 103, 217402 (2009)

[3] R. M. Stevenson et al., Nature 439, 179 (2006)

[4] J. Zhang et al., Nat. Commun. 6, 10067 (2015)

[5] Y. Chen et al., Nat. Commun. 7, 10387 (2016)

[6] R. Keil and M. Zopf et al., Nat. Com-mun. 8, 15501 (2017)

Many quantum information appli-cations (e.g. quantum repeaters)

rely on quantum interference between polarization-entangled photons from dif-ferent sources [1]. Quantum dots are among the leading candidates for deter-ministic semiconductor entangled-photon sources. However, their growth charac-teristics lead to a random distribution in emission energy, lifetime and coherence time. To ensure photon indistinguishabil-ity from different sources, deterministic post-growth tuning techniques become inevitable. Several tuning knobs can be exploited, e.g. electric [2], magnetic [3] or strain fields [4]. The recent develop-ment of a strain-tuning platform enables both tuning of the emission frequency and the fine-structure of quantum dots [5], re-alizing entangled-photon emission at a

desired frequency. Using this technique, we show that two InGaAs/GaAs quantum dots with zero fine-structure splitting can be tuned into resonance with each other, as a condition for two-photon interfer-ence between such sources. Furthermore, we exploit GaAs/AlGaAs quantum dots, which have recently shown to exhibit ex-ceptional entanglement fidelities, ultra-high yield, and narrow wavelength and fine-structure splitting distributions [6]. Using a two-photon excitation scheme, the quantum dots are excited coherently and deterministically, and therefore cir-cumventing the photon emission time jit-ter seen under non-resonant excitation. By performing fluorescence lifetime mea-surements and Fourier transform spec-troscopy, the photon indistinguishability is extracted.

Michael Zopf1, R. Keil1, Y. Chen1, F. Ding1,2, O. G. Schmidt1,3

1 Institute for Integrative Nanosciences, IFW Dresden, 01069 Dresden, Germany2 Institut für Festkörperphysik, Leibniz Universität Hannover, Appelstrasse 2, 30167 Hannover, Germany3 Material Systems for Nanoelectronics, TU Chemnitz, 09107 Chemnitz, Germany

Towards quantum interference between distant entangled-photon emitters

A watched quantum arrow does not move. This effect, referred to as the

quantum Zeno effect, arises from a fre-quent measurement of a quantum sys-tem’s state. In more general terms, the evolution of the quantum system can be confined to a subspace of the system’s Hilbert space leading to quantum Zeno dynamics. Resulting from the measure-ment process, a source of dissipation is introduced into the systems dynamics. However, different than for a common open quantum system, we can choose the strength of the dissipation by changing the parameters of the Zeno measurement.

We capitalise on the property of tunable dissipation to create a quantum simulator for open quantum systems. Due to the for-

mal analogy of the measurement process and the theory of open quantum systems, we can derive a Lindblad master equa-tion to describe the evolution of the open quantum system. Moreover, we extend the picture to enable also non-Markovian evolution in the quantum simulator.

The considered quantum system are pho-tons inside a cavity being subject to an indirect measurement using circular Ryd-berg atoms. The setup is inspired by Zeno experiments proposed in the framework of cavity quantum electrodynamics [1].

Sabrina Patsch and C. P. KochTheoretical Physics, University of Kassel, 34132 Kassel, Germany

References

[1] Raimond et al. Phys. Rev. A 86, 032120 (2012)

Quantum simulators for open quantum systems using quantum zeno dynamics

References

[1] A. Sarlette et al., Phys. Rev. Lett., 107, 010402 (2011)

[2] C. Sayrin et al., Nature, 477, 73–77( 2011)

[3] R. Gohm et al., Comm. Math. Phys., 352, 59–94 (2017)

[4] Z. Miao et al, Quantum Sci. Technol. 2, 034013 (2017)

Quantum reservoir engineering, which bypasses a real-time analysis of out-

put signals, is an important and effective approach for quantum state stabilization. Here, we consider a reservoir consisting of a sequence of input qubits, with the aim of manipulating and stabilizing the state of a harmonic oscillator indirectly via cou-pling with these qubits. This system setup (Fig. 1) is similar to that in [1], which is generally analogous to the Haroche ex-periment setting [2] but with no measure-ment-based feedback involved. The nov-elty of our present work is to investigate the effects of possibly entangling these qubits in time before they consecutively interact with the harmonic oscillator. This idea draws upon [3], where an abstract framework for bath-mediated controlla-bility is formulated without assuming the qubits to be independent.

The contribution of this work is twofold [4]. First, by considering the reservoir qu-bits as a “control input”, we establish the additional “quantum power” enabled by having entanglement in the input, from a pairwise case to a more widely distributed case, showing how it can be used to effec-tively improve the system performance. The result turns out to revolve around the stabilization of strongly squeezed states of the harmonic oscillator mode. We further find that the properties of the squeezed state stabilized by this engineered res-ervoir, can be tuned at will through the parameters of the input qubits, albeit in tradeoff with the convergence rate. Sec-ond, by taking a weakly interacting res-ervoir, the stream of entangled qubits can be pushed to the continuous-time limit. This thus paves the way towards develop-ing general methods to explicitly and ef-ficiently analyze the behavior of quantum systems under time-entangled inputs.

Zibo Miao and A. Sarlette QUANTIC lab, INRIA Paris, 2 rue Simone Iff, 75012 Paris, France.

Discrete-time reservoir engineering with entangled bath and stabilizing squeezed states

Figure 1. Framework of quantum reservoir engineering. The aim is to stabilize the system S at a target state by coupling it to another quantum system R, referred to as the reservoir, which is viewed as a stream of input quantum states that are discarded after interaction. The novelty of the present work, unlike previous work where the reservoir is considered to consist of independent subsystems, is to establish the effect of entanglement among the reservoir items.

Figure 2. Scheme of the reservoir with recursively entangled qubits. The stream of reservoir qubits, initially in the ground state, is sent through an entangler where each qubit is successively entangled with the qubit directly before and directly after it in time. The operation of the entangler is characterized by the propagator UE while reso-nant interaction between the oscillator and each qubit is given by the propagator Ur.

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Solid state qubits, such as the Nitro-gen-Vacancy (NV) center in diamond,

are attractive sensors for nanoscale mag-netic and electric fields, owing to their atomically small size. A major key to their success have been dynamical decoupling protocols (DD), which enhance sensitiv-ity to weak AC signals such as the field of nuclear spins from a single protein. How-ever, those methods are currently limited to signal frequencies up to several MHz.

Here we harness a quantum-optical effect, the Mollow triplet splitting of a strongly driven two-level system, to overcome this limitation. We microscopically under-stand this effect as a pulsed DD protocol and find that it enables sensitive detec-tion of fields close to the driven transition. To this end, we create a pair of photon-dressed qubit states which support a new transition with narrow linewidth. Gener-ally, our scheme is applicable to any qubit

but we consider sensitive detection of sig-nals close to the NV’s transition frequency (≈ 2 GHz). As a result, we demonstrate slow Rabi oscillations with a period up to ΩRabi

-1 ~ T2 driven by a weak signal field. The corresponding sensitivity could en-able various applications. Specifically, we consider single microwave photon detec-tion, as well as fundamental research on spin-phonon coupling.

T. Joas, Andreas M. Waeber, G. Braunbeck and F. ReinhardWalter Schottky Institut und Physik-Department, Technische Universität München

Jakob Wierzbowski, F. Sigger, M. Kremser, C. Straubinger, K. Müller and J. J. FinleyWalter Schottky Institut and Physik Department, Technische Universität München, Am Coulombwall 4, 85748 Garching, Germany

Long-lived quantum emitters in hBN-WSe2 van-der-Waals heterostructures

Sensing weak microwave signals by quantum control

References

[1] K. Ott et al., Opt. Express 24, 9839 (2016)

[2] B. Brandstätter et al., Rev. Sci. In-strum. 84, 123104 (2013)

Single atoms coupled to optical cavi-ties can be used to build up quantum

interfaces between stationary and flying qubits in a quantum network. By using fiber-based optical cavities, we expect to reach the strong coupling regime of cav-ity quantum electrodynamics with single trapped ions. Operating in this regime would enable quantum communication protocols to be carried out over long distances with enhanced fidelity and ef-ficiency.

The challenge in integrating fiber cavities with ion traps is that the dielectric fiber mirrors should be far enough from the ions so that they do not significantly al-ter the trap potential. On the other hand, as the cavity mode volume is increased,

optical losses due to deviations from the mirrors’ ideal spherical shape play a sig-nificant role. To address this, we have developed new CO2-laser ablation tech-niques for improved fiber-mirror struc-tures [1]. With the resulting fibers, we have constructed cavities with finesses up to 70,000 at a length of 550 microns. To integrate these cavities with ions, we have built a miniaturized calcium ion trap. Each fiber is mounted on a nanopositioner, en-abling adjustment of the cavity alignment in vacuum [2]. By developing methods to control the charges trapped on the fibers’ surfaces, we have coupled an ion to a cav-ity with a length of 500 microns and with finesse in excess of 30,000.

P. Jobez1, F. Kranzl1, F. R. Ong1, K. Schüppert1, Markus Teller1, B. Ames1, D. A. Fioretto1, K. Friebe1, M. Lee1, K. Ott2, S. Garcia2, J. Reichel2, R. Blatt1,3 and T. E. Northup1

1Institut für Experimentalphysik, Universität Innsbruck, 6020 Innsbruck, Austria2Laboratoire Kastler Brossel, ENS/UPMC-Paris 6/CNRS, F-75005 Paris, France3Institut für Quantenoptik und Quanteninformation der Österreichischen Akademie der Wissenschaften, 6020 Innsbruck, Austria

Towards strong coupling of a trapped ion to a fiber cavity

Dario A. Fioretto1, K. Friebe1, M. Lee1, M. Teller1, K. Schüppert1, F. R. Ong1, P. Jobez1, F. Kranzl1, R. Blatt1,2 and T. E. Northup1

1Institut für Experimentalphysik, Universität Innsbruck, 6020 Innsbruck, Austria2Institut für Quantenoptik und Quanteninformation der Österreichischen Akademie der Wissenschaften, 6020 Innsbruck, Austria

Entanglement routing in an ion-trap-based quantum node

References

[1] J. I. Cirac et al., Phys. Rev. Lett. 78, 3221 (1997)

[2] H.J. Kimble, Nature 453, 1023 (2008)

[3] N. Sangouard et al., Phys. Rev. A 79, 042340 (2009)

[4] A. Stute et al., Nature 485, 482 (2012)

[5] B. Casabone et al., Phys. Rev. Lett. 111, 100505 (2013)

Optical cavities can be used as efficient quantum interfaces to realize quan-

tum network applications ranging from quantum repeaters to distributed quan-tum computing [1,2]. In a future quan-tum network based on ions in cavities, photonic channels will link ions stored in remote cavities, with each ion-cavity sys-tem functioning as a node in the network. A key protocol that can be implemented in such systems is the distribution of en-tanglement to distant ions [3]. In recent years, we have investigated entanglement of two trapped ions in a cavity via herald-ing and studied photon emission of col-lective states of two ions [4,5].

In order to use our ion-trap system as a quantum network node, we require new capabilities. In particular, we need to es-tablish links with multiple remote nodes, which can be achieved by using multiple ions and by routing photons entangled with different ions to different locations. I will present a protocol for a determinis-tic routing based on an addressed Raman transition. Furthermore, I will discuss experimental progress toward its realiza-tion, including capabilities for single-ion addressing and quantum state tomogra-phy of multiple photons.

References

[1] A. Castellanos-Gomez et al., 2D Mater. 1, 011002 (2014)

[2] J. Wierzbowski et al., arXiv, arX-iv:1705.00348 (2017)

[3] P. Tonndorf et al., Optica 2, 347 (2015)

[4] M. Koperski et al., Nat. Nanotechnol. 10, 503–506 (2015)

[5] A. Srivastava et al., Nat. Nanotechnol. 10, 491–496 (2015)

We present detailed investigations of the optical properties of single pho-

ton emitters that form in 2D hBN-WSe2 van-der-Waals (vdW) heterostructures demonstrating the potential of hBN as a high quality environment for vdW hetero-structure devices.

The samples investigated are monolayer WSe2 crystals that are fully encapsulated within multi-layer hBN crystals using vis-coelastic stamping techniques [1]. We observe a reduction of the bulk WSe2

exciton linewidth to ~ 4 meV for both X0 and X- transitions, a reduction of 50% compared to WSe2 placed directly on Si/SiO2 substrates, arising from sup-pressed non-radiative decay channels due to the hBN encapsulation [2-3]. For low excitation power densities (P < 2 W/cm²), the emission spectrum is dominated by lo-calized sharp (FWHM < 1 meV) emission lines redshifted by ~100meV with respect to the exciton PL energies. Second-order

photon correlation measurements reveal clear photon anti-bunching behaviour of the localized emitters. Time-resolved PL measurements reveal a mono-exponential lifetime of ~ 15 ns, 5-fold longer than re-ported in recent works [4-5]. Polarization-resolved experiments show a significant fine structure splitting of single emission lines ranging from 0.5 meV to 1 meV.

Finally, we show measurements per-formed for hBN-WSe2 heterostructures prepared on a ZrO2 solid immersion lens (SIL). Hereby, we enhance the spatial res-olution by a factor of ~ 5x and determine an upper bound of the spatial extent of the localized emitters to be ~ 360 nm.

Our results demonstrate the potential of employing hBN as a high quality sub-strate for optimized optical properties of delocalized and localized emission of ex-citons in WSe2.

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List of List of Participants ParticipantsFirst Name Name Institute / University Poster #Shilan Abo Adam Mickiewicz University

Charles Adams Durham University

Wolfgang Alt Universität Bonn

Gustav Andersson Chalmers University of Technology Session 1 - P01

Daniel Arweiler Walther-Meißner-Institut

Thomas Astner TU Wien Session 1 - P05

Mete Atatüre University of Cambridge

Kyle Ballantine University of St Andrews Session 1 - P08

Shabir Barzanjeh Institute of Science and Technology Austria

Daniel Basilewitsch Universität Kassel Session 1 - P03

Christian Besson Walther-Meißner-Institut

Amita Bikram Deb University of Otago

Mäx Blauth Walter Schottky Institut Session 1 - P23

Manuel Brekenfeld Max-Planck-Institut für Quantenoptik

Howard Carmichael University of Auckland

Joseph Christesen Max-Planck-Institut für Quantenoptik Session 1 - P09

Severin Daiß Max-Planck-Institut für Quantenoptik

Alexandre Dareau TU Wien Session 1 - P11

Daniele De Bernardis TU Wien Session 1 - P19

Frank Deppe Walther-Meißner-Institut

Leo Dicarlo TU Delft

Fei Ding Leibniz-Universität Hannover

András Dombi Wigner Research Centre for Physics Session 1 - P14

Jinjin Du Okinawa Institute of Science and Technology Session 1 - P22

Peter Eder Walther-Meißner-Institut

Christopher Eichler ETH Zürich

Dirk Englund Stanford University

Klaus Ensslin ETH Zürich

Jürgen Eschner Universität des Saarlandes

Kirill Fedorov Walther-Meißner-Institut

Jonathan Finley Walter Schottky Institut

Dario Fioretto Universität Innsbruck Session 2 - P43

Michael Fischer Walther-Meißner-Institut

Mark Fox University of Sheffield

David Gershoni Technion - Israel Institute of Technology

Seyed Behdad Ghaffari Walther-Meißner-Institut

Rudolf Gross Walther-Meißner-Institut

Mustafa Gündogan Cambridge University Session 2 - P35

Bastian Hacker Max-Planck-Institut für Quantenoptik Session 1 - P16

Lukas Hanschke TU München Session 1 - P18

Jack Harris Yale University

Sebastian Hofferberth University of Southern Denmark

Hans Hübl Walter Schottky Institut

Jan Huwer Toshiba Research Europe

Tuomas Jaako TU Wien

Alisa Javadi University of Copenhagen

First Name Name Institute / University Poster #Markus Jerger The University of Queensland Session 1 - P21

Aisling Johnson TU Wien

Tobias Kampschulte Universität Ulm Session 1 - P15

Michael Kaniber Walter Schottky Institut Session 1 - P20

Mark Kasevich Stanford University

Robert Keil IFW Dresden Session 2 - P29

Jeff Kimble California Institute of Technology

Matthias Körber Max-Planck-Institut für Quantenoptik Session 2 - P25

Jörg Kotthaus LMU München

Stefan Langenfeld Max-Planck-Institut für Quantenoptik

Fabrice Laussy University of Wolverhampton

Wenfang Li Okinawa Institute of Science and Technology Session 2 - P38

Gang Li Max-Planck-Institut für Quantenoptik Session 1 - P17

Lin Li Max-Planck-Institut für Quantenoptik

Norbert Lütkenhaus University of Waterloo

Johannes Majer TU Wien

Luke Masters TU Wien Session 1 - P24

Jonathan Matthews University of Bristol

Milad Mehrpoo TU Delft Session 2 - P26

Gwenaelle Mélen TU München

Benjamin Merkel Max-Planck-Institut für Quantenoptik

Zibo Miao INRIA de Paris Session 2 - P42

Olivier Morin Max-Planck-Institut für Quantenoptik

Clemens Müller The University of Queensland Session 1 - P10

Petio Natzkin Walther-Meißner-Institut

Jonas Neumeier Max-Planck-Institut für Quantenoptik

ChiHuan Nguyen National University of Singapore Session 1 - P07

Dominik Niemietz Max-Planck-Institut für Quantenoptik

Anna Nolinder Walter Schottky Institut Session 2 - P27

Tracy Northup Universität Innsbruck

Joshua Nunn University of Bath

Luis Orozco University of Maryland

Oskar Painter Caltech

Scott Parkins University of Auckland

Adrian Parra Rodriguez U.P.V-E.H.U Session 1 - P02

Sabrina Patsch Universität Kassel Session 2 - P41

Wolfgang Pfaff Yale University

Benjamin Pingault University of Cambridge

Stefan Pogorzalek Walther-Meißner-Institut Session 2 - P28

Thomas Pohl Aarhus University

Simon Ragg ETH Zürich Session 2 - P34

Tomás Ramos Spanish Research Council (IFF-CSIC) Session 1 - P04

Arno Rauschenbeutel TU Wien

Andreas Reiserer Max-Planck-Institut für Quantenoptik

Gerhard Rempe Max-Planck-Institut für Quantenoptik

Lisa Rosenzweig Walther-Meißner-Institut

80 81

RQED 2017

List of ParticipantsFirst Name Name Institute / University Poster #Maximilian Russ Universität Konstanz Session 2 - P30

Michael Scheucher TU Wien

Philip Schmidt Walther-Meißner-Institut Session 2 - P31

Daniel Schwienbacher Walther-Meißner-Institut

Irfan Siddiqi UC Berkeley

Tobias Simmet TU München Session 2 - P33

Glenn Solomon University of Maryland

Markus Teller Universität Innsbruck Session 2 - P44

Daniel Tiarks Max-Planck-Institut für Quantenoptik

Nicolas Tolazzi Max-Planck-Institut für Quantenoptik Session 1 - P12

Adrian Nugraha Utama National University of Singapore

Christoph Utschick Walther-Meißner-Institut

Samarth Vadia LMU München

Denis Vion CEA Saclay

Juergen Volz TU Wien

Jelena Vuckovic Stanford University

András Vukics Wigner Research Centre for Physics

Vladan Vuletic Massachusetts Institute of Technology

Andreas Waeber TU München Session 2 - P46

Bo Wang Max-Planck-Institut für Quantenoptik Session 1 - P06

Stefan Weichselbaumer Walther-Meißner-Institut Session 2 - P36

Thomas Weissl KTH - Royal Institute of Technology

Stephan Welte Max-Planck-Institut für Quantenoptik Session 2 - P37

Jakob Wierzbowski Walter Schottky Institut Session 2 - P45

Frank Wilhelm-Mauch Universität des Saarlandes

Tatjana Wilk Max-Planck-Institut für Quantenoptik Session 2 - P39

Elisa Will TU Wien Session 1 - P13

Matthias Wulf Institute of Science and Technology Austria Session 2 - P32

Edwar Xie Walther-Meißner-Institut

Michael Zopf IFW Dresden Session 2 - P40

82

ContactIris SchwaigerMax Planck Institute of Quantum OpticsHans-Kopfermann-Str. 1, 85748 GarchingPhone: +(49) 89 3 29 05 - 711Fax: +(49) 89 3 29 05 - 311E-mail: [email protected]

VenueKardinal Wendel HausMandlstraße 23, 80802 München Phone: (+49) 89 381020Web: www.kwh.kath-akademie-bayern.de

Organizing CommitteeChristoph Hohmann Nanosystems Initiative MunichSilke Mayerl-Kink Nanosystems Initiative MunichIris Schwaiger Max Planck Institute of Quantum Optics Peter Sonntag Nanosystems Initiative Munich

Program CommitteeJonathan Finley Walter Schottky Institute, TU MunichRudolf Gross Walther-Meißner-Institute, TU Munich & Bavarian Academy of Sciences & HumanitiesGerhard Rempe Max-Planck-Institute for Quantum Optics, Garching

DisclaimerThe Organizers do not hold any liabilities on damages, losses, health issues, etc.. All participants are advised to take care about their travel and health insurances related to this conference.

AcknowledgementsWe gratefully acknowledge the generous support of the following organizations and institutions:

Documents

nanosystems initiative munich€¦ · Jonathan Finley, Rudolf Gross and Gerhard Rempe Welcoming Message Dear ... Overview Overview Session 1 ..... 10 Session 2 ... Session 5 Session