Discovery 2020

Yuta MichimuraDepartment of Physics, University of Tokyo

April 21, 2020Ando Lab Midterm Seminar

• Looking back on the year 2019

• Working from home

• My plans and expectations for the year 2020

• Hot topics (continued and expanded from 2019)

- Ultralight dark matter search with interferometers

- Optical levitation of photonic crystal mirror

- Lorentz invariance test in space

- SILVIA:Space

Interferometer

Laboratory

Voyaging towards

Innovative

Applications

Contents

2(c)Philip FONG / AFP

Review: My Plans JFY2019

3

Only upto ~0.97 Mpc

Mostly not done

Done for some tables

KAGRA+

paper not done

Work in progress

(Paper with Somiya-san

published)

SILVIA

Cavity constructed

New collaboration

started (PnC, LMA)

Review: My Expectations JFY2019

4

Successful implementation

Paper by Enomoto-kun

Not achieved

Partially done

DONE at below

100 Hz

Achieved good

sensitivity but not

started

Cryostat

constructed

PASSED

From this year?

DONE

Effort Report for 2019

5

• Compared with 2018:

- KAGRA slightly decreased, KAGRA+ halved

- Quantum and dark matter doubled

- DECIGO greatly increased

• Many visits (thank you for supports!)

Effort Report for 2019

6* Number of days spent was counted for each topic based on my personal record.

If n topics on the same day, 1/n was allocated for each topic.

For 2018

45.0%

19.9%

4.6%

0.0%

4.7%

2.3%

15.6%

8.0%

without Virgo

Effort Report for 2020 (so far)

7

• At first could not concentrate on work

• Now I’m used to it. No commuting is convenient.

• But I started to feel like I’m left behind

• Lucky that most of the work can be done remotely with my

brain and PC (which is not ideal for experimentalists, though)

Working from Home

8

Sleep Sleep

Eat

Eat

Eat

Eat

EatWorkWork

Commute

News

ShopChat

• I was expecting a decrease, but slightly increased?(may be just a coincidence)

Email Traffic over the Month

9

7都府県緊急事態宣言

https://emailanalytics.com/

Started to work from home

Test emails

to check

granite

• Significant achievements by group members

• New projects such as SILVIA, DANCE and optical levitation

mirror started as anticipated

• Progress in KAGRA much less than anticipated (found

tragedic issues: birefringence and frosting)

• Visited (too?) many places, gave a number of talks,

including lectures at TianQin Research Center and Durham

University, and met new people

• Wrote many applications (4 positions, 3 grants, involved in

other 6 applications including a big one on dark matter)

• Wrote EPJD review paper on mg-scale optomechanics,

Parity article on KAGRA

• New people related to dark matter

• Time to realize ideas rather than coming up with new ideas?

Summary and News from JFY2019

10

• 2019 was the most productive year by numbers

• But this is just from past activities of group members

Productivity for the Past 10 Years

11

As of April 2020

B4->M1

PhD Thesis

• First big decrease in our group

• 2020 will be the touchstone of our ability to keep up

Number of People in Ando Group

12

• Largest over the past years

• Largest output is expected

Grants for JFY2020

13

Lorentz violation

- observation!

Optical levitation

- mirrors!

Quantum

- mirrors!

Axion

- demonstration!

※間接経費含む

• Work-work balance would be

very important in coming years

• Large scale vs Table top

• Ongoing vs Emerging

• Management vs Implementation

……

Balance between Topics

14

• Remaining things for O4

- OMC, beam shutter

- Optical table cover for TRX and TRY

- upgraded MZM? In-vac RF PDs and RF/DC QPDs?

• Finish KAGRA+ paper, write birefringence paper

• More concrete planning of SILVIA and DECIGO

• Write SILVIA and DECIGO paper

• Absorption calculations for

optical levitation mirror

• Start DANCE Act-1 observation

• Introduce polarization optics

to TRX and TRY of KAGRA

• Search for ultralight dark matter

with KAGRA data

My Plans JFY2020

15

• New data analysis on GW polarization

• Better control of filter cavity and more clear squeezing angle

rotation

• Pave the way to optical levitation mirror (photonic crystal or

curvature from coating stress)

• Stability confirmation paper for optical levitation

• Start Lorentz violation search with upgraded setup

• Q measurement at cryogenic temperatures

• Coil-coil actuator paper

• New people in our group

My Expectations JFY2020

16

• June: 16th Patras Workshop @ Trieste, Italy

→ postponed to June 2021

• July: 13th LISA Symposium @ Glasgow, UK ??

• September: 日本物理学会@ 筑波大学, 熊本大学 ??

• September: 日本天文学会@ 弘前大学 ??

• September: LVKC @ Cardiff, UK ??

• October: JGRG30 @ 早稲田大学 ??

• March: 日本物理学会@ 東京大学駒場キャンパス ??

Schedules in JFY2020

17

• 2019 ver (see slides)

- DANCE: Dark matter Axion riNg Cavity Experiment

- Optical levitation of photonic crystal mirror

- Lorentz invariance test in space

- C-DECIGO: km scale GW detector in space

• 2020 ver

- Ultralight dark matter search with interferometers

- Optical levitation of photonic crystal mirror

- Lorentz invariance test in space

- SILVIA: Space Interferometer Laboratory Voyaging

towards Innovative Applications

Hot Topics

18

• Great tool to probe fundamental mysteries of our Universe

• Laser interferometric gravitational wave detectors can be

sensitive to various physics other than gravitational waves

• Small scale experiments can beat large scale experiments

Laser Interferometry

19

Laser

Length change

δL/L

Gravitational

waves

Axion

Lorentz violation

Speed of light

change δc/cFringe change

∝δL/L, δc/canisotropy

Quantization

of gravity

Mirror

displacement

Non-standard

forces

Dark

matter

Dark energy

polarization

dependence

B-L bosons

Cosmic expansion,

inflation

Alternative

polarization

modes

wave function

collapse

quantization of

spacetime

Boson cloud

around BHs

extra

dimensions

• We know they exist everywhere and

we know they played an important role

in forming our Universe,

but we don’t know what they are at all

Dark Matter

21

• Wide range of candidates, but many focused on WIMPs

• WIMP searches will be soon limited by neutrino background

Past Searches: WIMPs

22PBHs

(upto 100 Msun = 1e59 GeV)

Park (2007)

https://cerncourier.com/a/defeating-the-background-

in-the-search-for-dark-matter/

A New Era

23

G. Bertone, T. M. P. Tait, Nature 562, 51 (2018)

• Strong tool to search for ultralight dark matter (wave-like

dark matter)

• Dark matter Axion search with riNg Cavity Experiment

(DANCE)I. Obata, T. Fujita, YM, PRL 121, 161301 (2018)

• DM Axion search with laser interferometric GWDK. Nagano, T. Fujita, YM, I. Obata, PRL 123, 111301 (2019)

• B-L gauge boson searchP. W. Graham+, PRD 93, 075029 (2016)

A. Pierce+, PRL 121, 061102 (2018)

D. Carney+, arXiv:1908.04797

• Search through fine-structure constant changeH. Grote & Y. V. Stadnik, PRR 1, 033187 (2019)

• New searches with strong magnetsR. Creswick, F. T. Avignone III, arXiv:2004.01642

Laser Interferometric Search

24

DANCE

25

• Axion-photon coupling ( ) gives different

phase velocity between left-handed and right-

handed circular polarizations

• Measure the difference

as resonant frequency

difference in an bow-tie

cavity

coupling constant axion fieldaxion mass

• L= 1 m, Finesse = 3e3, Pin= 1 W

• Also good for practicing a cavity experiments

DANCE Act-1

26

∝ma0

∝ma1/4

∝ma5/4

Tcoh>Tobs cavity pole

∝ma1/2

scan

∝ma1/2

scan

∝ma1

∝ma5/4

• L= 1 m, Finesse= 2e5, Pin= 1 W, Tobs= 3 months

• New idea to do coherent search with two cavities

• Table-top experiment is complementary to large-scale

experiments like GW detectors

DANCE Act-2

27

γ-ray from SN1987A

CAST

Axio

n-p

hoto

n c

ouplin

g

DANCE Act-2

(two cavities)

X-ray from M87

KAGRA (3 km)

Advanced LIGO

(4 km)

DM Axion Search with GWDs• Different method is required for linear cavities in GW

detectors

• Axion-photon coupling create

modulation in polarization

angle of linear polarization

• Sensitive when modulation period and round-trip time of

light in a cavity are the same

• Can be searched

along with GWs

28

left-handedis faster

right-handedis faster

p-pol

Modulation at frequency

Laser FI

p-pol

s-pol(Axion signal)

p-pol(GW signal)

• Difference between baryon number and lepton number

• B-L is conserved very well and could be a charge of U(1)B-L

symmetry

→ It is natural to think that some gauge boson is coupled

• Related to baryon asymmetry

through leptogenesis

B-L Gauge Boson

29

Baryon Lepton

浜口幸一 (2017)

• Several groups proposed laser interferometric search with

GW detectors and mg-scale optomechanical experiments

P. W. Graham+, PRD 93, 075029 (2016)

A. Pierce+, PRL 121, 061102 (2018)

D. Carney+, arXiv:1908.04797

• When mirrors have different

B-L ratio (~neutron ratio), different

resonant frequency, or mirrors are

apart, amplitude or phase of force

acting on mirrors are different

and DM signal remains

Gauge Boson Search

30

• KAGRA can outperform aLIGO because of the use of

sapphire mirrors

• Table top experiment can also be used

Search with KAGRA and mg Mirror

31

When DM direction is optimal1 year observation with designed sensitivity for KAGRA and aLIGO

Sensitivity in PRL 122, 071101 (2019) is used for 7-mg pendulum

KAGRA PRC

KAGRA

DARM

Advanced

LIGO

EP tests7-mg pendulum

with fixed mirror

• Dark matter search could

bring light to KAGRA

bKAGRA to dKAGRA

32

Sensitive axion search with OFI rejected beam

B-L gauge boson search with POP beam

Add polarization optics to TRX and TRY to search for axion with lower sensitivity

JGW-P2011614

Fine-Structure Constant• Scalar DM may introduce temporal variation in α

• Variation in α can be searched by looking for

mirror thickness change

• BS thickness by MICH or ITM HR surface

position change by DARM

33

H. Grote & Y. V. Stadnik,

PRR 1, 033187 (2019)

• Axion-photon conversion under magnetic field

(Primakoff effect)

• LSW probability

• Sensitivity proportional to

Light Shining through Wall (LSW)

34

production γ→a reconversion a→γ

power build up

magnetic fieldcavity length

• See change in the transmitted power

• Modulate input laser polarization to modulate the signal

• Sensitivity will be proportional to

• But it is not a null measurement (room for improvement?)

Proposal to Improve the Sensitivity

35R. Creswick, F. T. Avignone III, arXiv:2004.01642

FPAS-100

B=10 T, L=100 m,

Finesse=1e5, Pin=7.5 W

ALPS-IIc

B=5 T, L=100 m,

Finesse=1.2e5, Pin= 30 W

Optical

Levitation

• Nov 2013: Sandwich proposed at a seminar

• Jan 2014: Ordered a prototype fused silica mirror

3 mm dia. t 0.1 mm, RoC= 30 mm, R>99.95 %

• Apr 2014: Delivered (6 out of 7 are broken)

• Oct 2014-Jan 2020: Torsion pendulum experiment- Feb 2015: B4 report by Aritomi and Enomoto

- Jan 2016: Master thesis by Kuwahara

- Jan 2018: Master thesis by Wada

- Jan 2019: Master thesis by Kawasaki

- Jan 2020: Master thesis by Kita

• Apr 2019: Proposal to use photonic crystal (seminar)

• Oct 2019: Horizontal restoring force confirmation (elog)

• Dec 2019: PCM collaboration initiated (seminar)

• Apr 2020: Ordered thin fused silica substrates

• Let’s fabricate and characterize of mirrors!

Long History

37

Levitation Mirrors We Want• First goal is to demonstrate the levitation

• For demonstration, heavier mirror with higher

finesse is OK

38

For SQL Prototype For suspended

experiment

Mass 0.2 mg ~1.6 mg ~ 7 mg

Size (mm) φ 0.7 mm

t 0.23 mm

φ 3 mm

t 0.1 mm

φ 3 mm

t 0.5 mm

RoC 30 mm convex 30±10 mm convex

(measured:

15.9±0.5 mm)

100 mm concave

(previously flat

ones were used)

Reflectivity 97 %

(finesse 100)

>99.95 %

(measured: >99.5%)

99.99%

Comment Optics Express 25,

13799 (2017)Only one out of 8

without big cracks

Succeeded

• Mirror transmission give mirror mass (and mirror radius)

• Mirror transmission also gives maximum beam radius

allowed from diffraction loss

Mirror Mass vs Reflectivity

39

Calculation by T. Kawasaki,

modified by YM(Mirror thickness 0.1 mm,

fused silica assumed to calculate radius.

Critical coupling)

97%, 0.2 mg

(for SQL)

If critical couple, no detuning

9.8 m/s2Mirror power

transmission

(R=1-T)

Intra-cavity power

99.95%, 1.6 mg

(for levitation demonstration)Beam radius should be smaller than 0.6 mm

Beam radius has

to be smaller than

dotted lines

(2*Taperture < Tcoat/10)

• Raw Si3N4 membrane (Norcada NX5100DS)

- we have one

• Membrane with photonic crystal

- we need to fabricate

• 3 mm dia. mirror we made in 2014

- we have one

• 3 mm dia. thin fused silica substrate

- in stock, ordered

• 1 inch dia. thin fused silica mirror

- available by summer?

• 3 mm dia. thin fused silica mirror

- available by the end of summer?

Mirrors to Characterize in 2020

40

• By beam profiling of reflected beam and by cavity scan

(Nagano method; see JPS2017s talk)

• Inside the small chamber to avoid contamination of mirrors

• See Chiyoda-kun’s talk

Characterization Method

41

• Steady state temperature can be roughly calculated with

• Absorption of <~10 ppm is necessary (sounds reasonable)

Absorption

42

- Fused silica assumed

- Thickness 0.1 mm assumed

for calculating surface area

- Actual temperature increase

will be higher by x~2 if upper

cavity is also considered

Temperature for disk shape

saturates when

radius >> thickness

since m, Pcirc and A will be

proportional to radius2

Surface areaMirror temperature

Environment temperature

Emissivity(~0.99) Stefan-Boltzmann constant

Absorption

• Since beam density is high, two-photon absorption might

also have to be considered

• The effect of temperature increase to

- Radius of curvature change

- Thermal lensing, wave front distortion

- Cavity length change

etc…

should be considered with simulations(fused silica melting point is ~2000 K)

• Absorption measurements also necessary

• Study on photothermal effects recently reported by ANU

R. Lecamwasam+, arXiv:1912.07789

(if mirror heating increases cavity length, single optical

spring can stabilize the cavity length)

More on Absorption

43

Nanosphere is Hot

44

Even though absorption islow, high temperatures (2,000 K) can be reached because of poorheat transfer to the surrounding gas at low pressures. J. Millen+, Nature

Nanotechnology 9, 425 (2014)

Lorentz

Violation

• Mar 2011: Monolithic MI experiment at Kyoto (seminar)

• Jul 2011: Proposal for ring cavity at seminar

• Jul 2012 to Oct 2013: Observation run

• Jun 2013: CPT’13 conference (seminar)

• Oct 2014: Submission of PhD thesis

• Jan 2018: Master thesis by Sakai and Takeda

- Continuous rotation

and monolithic optics

• Oct 2019: Almost the same

noise floor at stationary

and rotation achieved

by Takeda-kun

Even Longer History

46

Apparatus Comparison

47

turntable

laser

semi-monolithic

optics

vacuum enclosure

data logger

AC power

turntable

laser

non-monolithic

optics

vacuum enclosure

data logger

AC power

rotary

connector

Old Model

- non-monolithic optics

- alternative rotation

New Model

- monolithic optics

- continuous rotation

PC

PC

wireless

• Floor noise at rotation stays almost the same with that at

stationary

• Noise peak at rotation frequency

Latest Sensitivity

48

When rotating

(old)

When rotating

(new)

Stationary

(old)Stationary

(new)

Polarization?

Intensity?

Could be solved

with fiber fusion

splicing

• Good results are obtained and we need to take the last step

toward the observation (may be its better to just start now?)

• Also can be used for practicing cavity control and noise

hunting

• Setup very close to the setup which can be brought into

space (see seminar slides)

Prospects in 2020

49

http://qsfp.physics.ox.ac.uk/

• 100 m triangular formation flight demonstration satellite

• Applied for JAXA’s Epsilon class mission (公募型小型)

• Some people previously called FF-DECIGO

• Demonstration for space GW detector

SILVIA

51

• 100 m, 100 g, finesse 100, 10 mW, 1e-13 N/rtHz

Sensitivity

52

SILVIA

TOBA

B-DECIGO

LISA

TianQin

B-DECIGO

LISA

aLIGO

Cosmic Explorer

Einstein TelescopeKAGRA

Control

Scheme

53

Laser

GW signal

frequency

servo

length

servo

drag-free

servo

• Initial link acquisition scheme and lock acquisition scheme

• Demonstration of control scheme with table top experiment

• Simulation of orbital motion with drag-free and cavity

controls taken into account

• Development of actuators and local sensors

• Basic ideas are discussed (in Nagano-kun’s thesis or here

and here), but actual demonstration

in table-top experiments and

time-domain simulations

are very important

• No need to care so much about

noise, focus on scheme

• Launch planned in ~2027

Interesting Topics for SILVIA

54

• Ultralight dark matter search

- DANCE Act-1 cavity experiment(cavity characterization, noise spectrum…)

- Observing run and data analysis pipeline(similar to continuous wave search;

we are taking KAGRA PRCL and MICH data now!)

• Lorentz violation search

- Hunt for noise peaking at rotation frequency(alignment, scattered light, fiber splicing…)

- Observing run and data analysis pipeline (similar to DM search)

• Optical levitation

- Mirror characterization

- Absorption calculation

• SILVIA

- Simulation on controls

- Demonstration experiment

Job Advertisement

55

* Red ones can be

done from home

• 2020 seems to be an important year for future discovery

• Only you can

motivate yourself

Summary

56