6-ccpr metrology for quantum communication sept2016 - BIPM€¦ · Source Spectrum Wavelength • Optical pulses of duration < 100 ps • Spectral width: ∆νsource ~ 12 GHz (@1550

METROLOGY

FOR

QUANTUM COMMUNICATION

Giorgio Brida

[email protected]

Workshop on Fiber Optics Metrology needs19 September 2016 Paris, BIPM

Metrology for Industrial

Quantum Communications

Sept. 2011 – Aug. 2014

Workshop on Fiber Optics Metrology needs - 19 September 2016 Paris, BIPM

Project Partners

Metrology for Industrial Quantum Communicationshttp://www.miqc.org/


Optical metrology for

quantum-enhanced secure telecommunication

July 2015 – June 2018

This project follows on from EMRP project MIQC


Optical metrology for

quantum-enhanced secure telecommunicationhttp://www.miqc.org/

Project Partners


• Objective : to develop a pan-European

measurement infrastructure to develop standards

and characterisation facilities for commercial

Quantum Key Distribution (QKD) devices.

• QKD devices require independent physical

characterisation in order to convince end-users

that the technology is working within specification

• Focus on faint-pulse (weak coherent pulse) QKD

over fibre at 1550 nm



These projects work closely with the ETSI

Industry Specification Group on QKD

ETSI ISG-QKD

Standardisation


Photon emitters Traceable characterisation of commercial QKD sources:

• Attenuated laser pulses

Photon receiversTraceable calibration of commercial QKD receivers:

• Gated photon counting detectors

Quantum channel (optical fibre) and RNG • Traceable characterisation of single mode optical fibre

• Characterisation of propagation of photon state in single mode fibre

• Open system true physical quantum random number generator (QRNG)

• QRNG physically characterised and tested under different operating

conditions

Focus on faint-pulse (weak coherent pulse) QKD over fibre at 1550 nm

24-27 June 2014







Key Measurement Outputs of MIQC





conditions

24-27 June 2014



Detectors’ parameters considered [1/2]Parameter Symbol Units Definition Measurement approach

Photon detection

probability

h probability/

gate

The probability that a photon incident at

the optical input will be detected within a

detection gate.

Via a calibrated laser light

source and a calibrated filter

Dark count

probability

Pdark (probability

/gate)

The probability that a detector registers a

detection event per gate, despite the

absence of optical illumination.

As above (1)

Afterpulse probability Pafterpulse (probability

/gate)


false detection event in the absence of

illumination, conditional on a true photon

detection event in the preceding detection

gate.

As above (1)

Dead time Tdead ns/µs The smallest time duration after which the

detection efficiency is independent of

previous photon detection history.

Via a train of two optical

pulses with tuneable temporal

separation

Recovery Time Trec ns/µs The time duration after a photon detection

event for the detection efficiency to return

to 99% of its steady-state value. This is only

important if the detector is passively

quenched

As above (4)

Receiver’s Detectors

24-27 June 2014Workshop on Fiber Optics Metrology needs - 19 September 2016 Paris, BIPM

Detectors’ parameters considered [2/2]Parameter Symbol Units Definition Measurement approach

Maximum count rate Cmax MHz/GHz The maximum rate of photon detection

events under strong illumination condition

in the single/few photon/gate regime.

This will be determined by the

photon detection efficiency,

the dead time, and dark

counts

Timing jitter Tjitter ps/ns The uncertainty in determining the arrival

time of a photon at the optical input.

Measure the FWHM in the

distribution of detection times

Maximum clock

frequency

Fmax MHz/GHz The maximum clock frequency at or below

which a detector can be operated in a QKD

system without giving rise to an intolerable

bit error rate.

Spectral Responsivity Rs unitless The photon detection efficiency as a

function of wavelength of the incident

photons.


source with known

wavelength (wavemeter) and

a calibrated filter

Receiver’s Detectors


Detectors’ parameters considered [1/2] (again!)

Parameter Symbol Units Definition Measurement approach

Photon detection

probability

h probability/

gate

The probability that a photon incident at

the optical input will be detected within a

detection gate.


source and a calibrated filter

Dark count

probability

Pdark (probability

/gate)


detection event per gate, despite the

absence of optical illumination.

As above (1)

Afterpulse probability Pafterpulse (probability

/gate)


false detection event in the absence of

illumination, conditional on a true photon

detection event in the preceding detection

gate.

As above (1)

Dead time Tdead ns/µs The smallest time duration after which the

detection efficiency is independent of

previous photon detection history.

Via a train of two optical

pulses with tuneable temporal

separation

Recovery Time Trec ns/µs The time duration after a photon detection

event for the detection efficiency to return

to 99% of its steady-state value. This is only

important if the detector is passively

quenched

As above (4)


Optical power traceability chain (SI)

0.005 % uncertainty

visible wavelengths,0.5 mW,collimated, free-space laser radiation

1 % uncertainty (k = 2)

1550 nm,100 pW,output from optical fibre

Primary standardCryogenic radiometry

NMI reference detectors

Low power reference detector


Φ = N (hc/λ)

N

Air coupling, 2mm beam

Uncertainty ≈ 100 ppm

Air/fibre coupling, ≈ 10 μm beam

Uncertainty ??

100 dB

SPAD

TES

SSPD

TRACEABILITY

- Stability

- Beam shape

- Background

- … !!!

532 nm -2,74 dB

633 nm -1,99 dB

850 nm -0,71 dB

1550 nm +1,90 dB

Optical power traceability chain (SI)

200 µW ECSR


PTB CryogenicRadiometer

PTB CryogenicRadiometer

PTB referenceInGaAs detectorPTB reference

InGaAs detector

Metrology Light Source –

dedicatedelectron storage

of PTB

Metrology Light Source –

dedicatedelectron storage

of PTB

SuperconductingSingle Photon

Detector

SuperconductingSingle Photon

Detector

Novel reference for calibrating single-photon

detectors based on synchrotron radiation

Exploitation of strict proportionality of ring current and emitted radiation

Number of stored electrons changes spectral radiant power over 11orders of magnitude without changes to the emitted spectrum

910≈−eN 310≈−e

N

24-27 June 2014

QESSPD* = count rateSSPD number of stored electrons ( I low )

photon rateTrap number of stored electrons ( Ihigh )











conditions











conditions



Source parameters considered [1/2]


Frequency (Rep.

Rate)

F Hz The frequency set by the

pulse generator

Measure via standard traceable frequency calibration

techniques

Mean photon

number

µ Photons

/pulse

Average number of

photons per pulse emitted

by Alice

a) calibrated detector and commercial attenuator

b) calibrated detector and traceable attenuator based

on InGaAs photodiodes

c) reconstruction of probability distribution

d) Photon number resolving detector based on

commercial single photon detector in tree

configuration

Mean photon

number variation

σµ As above

Source timing jitter JS ps or ns The uncertainty in the

emission time of a photon

at the optical output.

Measure FWHM of distribution of photon emission times

with respect to pulse generator signal

Emitter’s Sources


Source parameters considered [2/2]


Source wavelength λ nm Wavelength of photons

that are emitted.

Wavemeter

Spectral line width δ GHz Bandwidth of the emitted

photons.

Beat note measurement or Fabry-Perot interferometer.

Spectral

indistinguishability

sind Unitless The extent to which the

encoded states can be

distinguished through

spectral measurement.

Fabry-Perot interferometer: compare spectra of different

encoding states

Temporal


tind Unitless The extent to which the



temporal measurement.

The probability distribution with respect to time for laser

output pulses is measured. tind is calculated according to

reference [12].

Polarisation state Polarisation reconstruction

Emitter’s Sources


Source parameters considered [1/2] (again!)


Frequency (Rep.

Rate)

F Hz The frequency set by the

pulse generator

Measure via standard traceable frequency calibration

techniques

Mean photon

number

µ Photons

/pulse

Average number of

photons per pulse emitted

by Alice

a) calibrated detector and commercial attenuator

b) calibrated detector and traceable attenuator based

on InGaAs photodiodes

c) reconstruction of probability distribution

d) Photon number resolving detector based on

commercial single photon detector in tree

configuration

Mean photon

number variation

σµ As above

Source timing jitter JS ps or ns The uncertainty in the

emission time of a photon

at the optical output.

Measure FWHM of distribution of photon emission times

with respect to pulse generator signal


Source photon number statistics

Reconstruction of probability distribution

Photon number distribution

For on/off detectors like SPAD with quantum efficiency �, the probability of no-

clicks is:

“ON/OFF” Tomography

-Truncating the p.d. to a certain �

-Changing the value of the quantum efficiency��

Poissonian

Reconstructed



1310 nm laser

Transition Edge Sensor i.e. µcalorimeter working at

superconductive phase transition



d) PNR detector based on tree configuration

Detector Tree:

4 click/no-click

detectors

BS

BS

BS

( )( )

(2) (3) (4) ( ), , 1

nn

P ng g g g

P=

• By measuring higher-order g(n), it is possible to deconvolve

the underlying number and kind (poissonian, pseudo-

termal or single-photon) of occupied modes of a light field.

Deconvolving the p.d. of incoming photons

Goldschmidt et al., PRA

88, 013822 (2013)

24-27 June 2014

• Novel (entanglemet-assisted) quantum

characterisation technique for PNR

detector Brida et al., PRL 108, 253601 (2012)




that are emitted.

Wavemeter


photons.


Spectral






Fabry-Perot interferometer: compare spectra of

different encoding states

Temporal






The probability distribution with respect to time for

laser output pulses is measured.




Source Spectrum

Wavelength

• Optical pulses of duration < 100 ps

• Spectral width: ∆νsource ~ 12 GHz (@1550 nm)

• Target uncertainty in λsource of δλsource < 0.01 nm (1.2 GHz @1550 nm)

Wavemeter measurement

• Needs to be high flux (before attenuation)

• standard interferometer design not necessarily good for pulsed laser

• can use alternative design (eg High Finesse) suitable for pulsed sources


Source Spectrum

Tunable single-photon spectrometer

• Operating range 1270 → 1630 nm

• FSR = 119 GHz, ∆νcavity = 600 MHz

• Low drift rate & single-photon sensitivity

• Tune to resonance and scan across QKD source spectrum

• Can be used to analyse different source encoding spectra

• Technically challenging to improve spectral resolution




that are emitted.

Wavemeter


photons.


Spectral






Fabry-Perot interferometer: compare spectra of

different encoding states

Temporal






The probability distribution with respect to time for

laser output pulses is measured.




Noiseless Heralded SPS

HBTHBT

∆tswitch

24-27 June 2014

g(2) =

∆tswitch = 2ns

Brida et al., APL 101, 221112 (2012)











conditions











conditions

Phase encoded, attenuated laser pulse QKD over fibre at 1550 nm


Polarization state reconstruction

- CW or quasi-CW source before attenuation: conventional polarimeter

- Pulsed source (challenging)

- Attenuated Source (single-photon light level): quantum state tomography

- Issue: polarization stability

Evaluation of the parameters: {S1 , S2 , S3}

3 projective measurements: :


MIQC 2http://www.miqc2.org/

MIQC 2WP1: Counter-measures and novel optical

components for commercial fibre-based QKD

The aim of this work package is to characterise and validate counter-measures to side-channel

and Trojan-horse attacks in order to ensure the security of fibre-based QKD systems. This

activity is carried on in strict collaboration with the ETSI Industry Specification Group on QKD.

• Identify vulnerabilities of passive and active

components

• Develop and verify counter-measures

• Develop security models

• Characterise a new, high-speed, type of SPAD

• Intercomparison of fibre-coupled DE and g2


MIQC 2WP2: Metrology for commercial components for

free-space QKD

The aim of this work package is to establish measurement and characterisation facilities for

components of free-space QKD devices. Within the scope of this project, we define the spectral

range as that where silicon-based detectors are applicable, i.e. between 400 nm and 950 nm.

• Develop characterisation facilities facilities for

free-space QKD components

• develop tests for Quantum Random

Generators

• absolute reference detector for in-situ

calibration of SPADs

• Intercomparison of free-space DE and g2Workshop on Fiber Optics Metrology needs - 19 September 2016 Paris, BIPM

MIQC 2WP3: Metrology for next generation (entanglement-

based) QKD

The aim of this work package is to foster the development of a measurement infrastructure for

entanglement-based (next-generation) QKD systems, such as device-independent,

measurement device-independent and reference-frame independent QKD.

• Develop metrics and measurement apparatus

for entanglement and quantumness

quantification

• Apply to key properties of measurement-

device-indipendent QKD


MIQC 2

Joint Virtual European Metrology Centre for Quantum Photonics

… a general objective of the project is investigating thepossibility of establishing the “Joint Virtual EuropeanMetrology Centre for Quantum Photonics” between thepartners. A strategic analysis for the creation of this Centre willbe carried out, which will include consultation with stakeholdersand CCPR, and report on the need and proposed terms-of-reference for this Joint Centre.

IMPACT


Achievements

�SPAD back-flash emission done� pilot comparison of SPAD d.e. started

� entanglement meas. for QKD applications on going

� Fiber link 640 km QKD INRIM-LENS (Florence) on going

MIQC 2


Photon-counting

optical time-domain reflectometry

at 1550 nm

Back-flash from SPAD


NEWRAD 2014, 24-27 June, Espoo

Pulse

generator

Pulsed

laser

Optical

attenuator

Correlator

Free running

SPADID300

ID220

Fibre optic

device

circulator

sync



0 5 10 15 20 25 30

10

100

1000

104

105

106

107

Co

un

ts

t/µs

Round & trip

SPAD dead time

1 km fibre

Rate 10 kHz

α = 33 dB

T = 1 h

bin = 1,024 ns



Pulse

generator

Pulsed

laser

Optical

attenuator

Correlator

Free running

SPADID300

ID220

SPAD

circulator

sync


0 50 100 150 200

10

100

1000

Co

un

ts

t/ns t/ns

SPAD - OFF


Co

un

ts

t/ns

0 50 100 150 2001

10

100

1000

t/ns

SPAD - ON


Co

un

ts

t/ns 0 50 100 150 200

1

10

100

1000

t/ns

SPAD - OFF


Co

un

ts

t/ns

0 50 100 150 200

10

100

1000

104

t/ns

SPAD - ON



SPAD - ON

Increasing the excess

bias voltage


I-QB POINT-TO-POINT LINK


First phase: december 2015

INRIM

SANTHIA’Link: INRIM –SANTHIA’

92 Km, -27 dB losses

• Clavis 3 system (Emitter & Receiver)

• 2xID230 external detectors : SKR >10 bps @ 30 dB

• 2 PC or Laptop to control Clavis 3 units


ITU29 1554.29nm

ITU32 1551.72nmFC/APC

ITU30 1553.33nm

FC/APC

Alice Bob

Clavis3

Quantum channel

(dark fiber)

FC/PCSMA

FC/APC

SMA

FC/PC

FC/APC

SMA

SMA

Ethernet (LAN)

ITU30

ITU29

WDM WDMClavis3

AMPLIF.

+ FILTER

ITU29

ITU30

ADD

DROP

ADD

DROP

Ethernet (LAN)

PC/Laptop

PC/Laptop

ID230

ID230

Classical channel

19” rack 19” rack

2x LC/PC 2x LC/PC

Ethernet (WAN)

Ethernet (WAN)

Power consumption of

the Clavis3: <250W

(220AC)


I-QB: 1st Meeting: October 14th, 2015

Second phase: december 2016-2017

• Optimisation of first phase link

• SKR >10 bps @ 30 dB

• Link: INRIM – UNIFI-LENS

• 642 km, -171 dB losses

• Sub-link losses: -25 to -34 dB

• 7 TN and 6 sub-links

• Detectors at 4 nodes

• TNs architecture to transmit securely

the secret key over long distances


Documents

6-ccpr metrology for quantum communication sept2016 - BIPM€¦ · Source Spectrum Wavelength • Optical pulses of duration < 100 ps • Spectral width: ∆νsource ~ 12 GHz (@1550