Metrology for QKD - a quantum optical communication technology
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Transcript of Metrology for QKD - a quantum optical communication technology
7/27/2019 Metrology for QKD - a quantum optical communication technology
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© Q u e e n ’ s P r i n t e r a n d C o n t r o l l e r o f
H M S O
, 2 0 1 3
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1 0 6 2 7 / 1 0 1 3
Receiver characterisationDE, DCP, APP
A bre optic power meter is calibrated at the 100 pW level,traceable to the cryogenic radiometer (1). The calibrated power
meter measures the output of a pulsed laser, transmitted through
a calibrated variable attenuator, at a similar power level (2). The
attenuator reduces the pulse output to the single photon level,
which is used to calibrate the QKD receiver (3). The laser pulses aresynchronised to the QKD detector gates, which can be operating
at a 1 GHz gate frequency. Uncer tainty (k=2) ~ 1-2 %.
Objective To develop a pan-European measurement infrastructure to develop standards andcharacterisation facilities for commercial Quantum Key Distribution (QKD) devices.
• QKD is a physical (as opposed to algorithmic) process
• Security depends on physical performance of system at time of key creation (as well asalgorithmic post-processing)
• QKD devices therefore require independent physical characterisation in order toconvince end-users that the technology is working within specication
• Focus of project is on optical layer of faint-pulse (weak coherent pulse) QKD, using
phase encoding in bre, and operating in the 1550 nm spectral region
Transmitter
• Mean photon number(s) (µ)
• Probability distribution
• Temporal pulse jitter, duration
• Wavelength
• Spectral bandwidth
• Spectral indistinguishability(with respect to phase setting)
Tunable single-photon spectrometer
Operating range 1270→ 1630 nm
FSR = 119 GHz
Δνcavity
= 600 MHz
PNR detector tree structure
• Four click/no-click detectors (commercial SPADs)
• Three pigtailed commercial 50:50 beam splitters
• Smart gating to minimise detector dead-time eects
An open system QRNG
Heralded single photon sourceBrida et al., Appl. Phys. Lett. 101, 221112 (2012)
Scaleable source based onsynchrotron radiation forcalibrating single-photon receivers
ETSI QKD-ISG
• An Industry Specication Group (ISG) of the European Telecommunications Standards Institute (ETSI) brings togetheractors from all over the world from science, industry, and commenceto address standardisation issues in quantum cryptography, andquantum technology in general.
• INRIM, NPL, and PTB who are members of the ETSI QKD-ISG, facilitateinformation exchange between the ISG and MIQC
• These laboratories have contributed to the ISG Group Specication
document – ‘Quantum Key Distribution (QKD); Components andInternal Interfaces’
Transmitter characterisation
Applying current capability to QKD
Key parameters identied for characterisation
Advances beyond existing capability
Channel• Spectral attenuation
• Chromatic dispersion
• Optical length
• Backscatter
• Polarisation mode dispersion,dependent loss, decoherence
• Wavelength multiplexed brelink performance
Receiver
• De tection e ciency (DE)
• Detection linearity
• Dark count probability (DCP)
• After-pulse probability (APP)
• Deadtime and recovery time
• Temporal jitter
• Back-ash
• Detector indistinguishability(multi-detector receiver)
Mach-Zehnderinterferometer
Mach-ZehnderinterferometerPulsed laser
Random setting
Random setting
Detector 2
Detector 1
Intensitymodulator
Phasemodulator
Phasemodulator
Attenuator
Transmitter (Alice)
Receiver (Bob)
Rationale
Metrology for QKD –a quantum optical technology
C J Chunnilall, I P Degiovanni, S Peters, A G Sinclair
IND06: Metrology for Industrial Quantum Communications www.migc.org Sep 2011 – Aug 2014
System optimisation
Measured μ, Δμ
Expected QBER, ΔQBER
- Bit rate and distance
- Privacy amplication
System stability
‘Natural’ change;
Performance-changing attacks
Security from hacking
(Side-channels)
Basis and bit indistinguishability
(pulses, detectors)
QKD
European Association of National Metrology Institutes
Requires measurement of the physical parameters of the system
QKD transmitter (pulsedsource, various mu values)
Synchronisation
Strict proportionality of ring current and emitted radiation
Can vary spectral radiant power over 11 orders of magnitude without changing emitted spectrum
Calibrated, gated photoncounting detector
µ
A gated photon counting detector is calibrated in a similar fashion
to that shown on the left for a QKD receiver. This measures the mean
photon number, μ, of the pulses emitted by the QKD transmitter.
Systems utilizing a decoy state protocol will require various μ values to
be measured. The detector gates are synchronised to the transmitter
pulses, which may be operating at a 1 GHz gate frequency. Uncertainty(k=2) ~ 1-2 %.
See Friday 9.40 talk – S V Polyakov et al. See Thursday 10.50 talk – M Legré et al.See Friday 11.25 talk – C J Chunnilall et al.
S ee : We dn es da y p os te r – I P De gi ov an ni e t a l. , Tu es da y ta lk 1 4. 25 – A To si e t a l. S ee We dn es da y po st er – I M ü ll er, S Kü ck , a nd R M Kl ei n h tt p: // ww w. et si .o rg /t ec hn ol og ie s- cl us te rs /t ec hn ol og ie s/ qu an tu m- ke y- di st ri bu ti on
PTB CryogenicRadiometer
PTB referenceInGaAs detector
Metrology LightSource – dedicated
electron storageof PTB
SuperconductingSingle Photon
Detector
Is it performing as it should?
: –I
–
Low-jitter detectors and high-bandwidth switch controller made it possible toreduce Δt
switch, reaching much better discrimination and g(2)(0) values.
Spectral indistinguishability
Tool for single photon characterisation Improved accuracy Standards
Probability distribution Random settings
Primary standardCryogenic radiometer
Synchronisation
Calibrated bre opticpower meter
Pulsed laser Calibrated variable attenuator QKD receiver (gated photoncounting detector)
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