Infrared superconducting single-photon detectors Robert Hadfield Heriot-Watt University, Edinburgh,...

Infrared superconducting single-photon detectors

Robert HadfieldHeriot-Watt University, Edinburgh, UK

Chandra Mouli Natarajan, Mike Tanner, John O’Connor Heriot-Watt University, UKBurm Baek, Marty Stevens, Sae Woo Nam NIST, USAShigehito Miki, Zhen Wang, Masahide Sasaki NICT, JapanSander Dorenbos, Val Zwiller TU Delft, The NetherlandsJonathan Habif, Chip Elliot BBN Technologies, USAHiroke Takesue NTT, JapanQiang Zhang, Yoshihisa Yamamoto Stanford, USAAlberto Peruzzo, Damien Bonneau, Mirko Lobino, Mark Thompson, Jeremy O’Brien U. Bristol, UK

• Introduction to photon counting• Superconducting nanowire single photon detectors

(SNSPDs): device concept and evolution.• Applications of SNSPDs in quantum information science:

measurements of quantum emitters, quantum key distribution, quantum waveguide circuits.

• Outlook: challenges and opportunities for this technology.

Infrared superconducting single-photon detectors

Robert Hadfield – RIT Detector Virtual Workshop 2011

• The term ‘Photon’ coined in 1926 following Einstein’s explanation of the photoelectric effect. Quantum of electromagnetic radiation E=hn.


What is a Photon?

What is a Photon?• The term ‘Photon’ coined in 1926 following Einstein’s explanation of the photoelectric effect. Quantum of electromagnetic radiation E=hn.

• Some prominent detractors:Willis Lamb ‘Anti-Photon’ Appl. Phys. B 60 77 (1995)

Indian Proverb:Six wise men went to see an elephant (though all of them were blind)..


• The term ‘Photon’ coined in 1926 following Einstein’s explanation of the photoelectric effect. Quantum of electromagnetic radiation E=hn.

• Some prominent detractors:Willis Lamb ‘Anti-Photon’ Appl. Phys. B 60 77 (1995)

• The following definition appears to cut the Gordian Knot:

‘A photon is what a photodetector detects’ (Roy Glauber)


What is a Photon?

Photon-counting detectors

• Human eyes are sensitive down to the (few) photon level.

• Photomultipliers photocathode + dynode multiplication

• Semiconductor single-photon avalanche photodiodes (SPADs)

• Superconductorsnumerous detector examples, including superconducting nanowires


• Human eyes are sensitive down to the (few) photon level.

• Photomultipliers photocathode + dynode multiplication

• Semiconductor single-photon avalanche photodiodes (SPADs)

• Superconductorsnumerous detector examples, including superconducting nanowires

Photon-counting detectors


InGaAs SPADs

Applications

Detectors

Single-photon detectors & applications

Wavelength

Life SciencesFLIM/FRET

Free space comms and LIDAR

Quantum cryptography

in fibre

Quantum Optics

Atmospheric Sensing

Astronomy

IC Testing

Photomultipliers IR PMTs

Si SPADs

Superconducting detectors


Characteristics of single-photon detectors

• High quantum detection efficiency at wavelength of interest.

• Probability of noise-triggered ‘dark counts’ low.

• Time between detection of photon and generation of electrical signal should be constant – low jitter.

• Short recovery time (‘dead time’).

• Ability to resolve photon number.

Review article: Hadfield RH ‘Single-photon detectors for optical quantum information applications’ Nature Photonics 3 (12) 696 (2009)


Superconducting nanowire single photon detectors (SSPDs or SNSPDs)

Key Properties:

• Wide spectral range (visible – mid IR)• Free running (no gating required)• Low dark counts• Low timing jitter• Short recovery time

Considerable scope for further improvements!

Gol’tsman et al Applied Physics Letters 79 705 (2001)


Sapphire substrate

NbN

Gol’tsman et al., Applied Physics Letters 79, 705 (2001)

100 nm

3.5 nm

Bias CurrentIncidentPhoton

Hot spot(R > 0)

Bias Current

Current densityabove critical

Hot spot(R > 0)

Bias Current

R > 0

Bias Current

R = 0 → Voltage Drop = 0

Superconducting nanowire single-photon detector

T~ 4K



V(t)

T~ 4KBias Current Reduced

R > 0 → Voltage Pulse Out

Hotspot Growth

Gol’tsman et al., Applied Physics Letters 79, 705 (2001)

Sapphire substrate

NbN


Sapphire substrate

NbN


Bias Current

Recovery: • Hotspot shrinks as heat is dissipated into substrate• Current builds up limited by inductance of nanowire

V(t)

Bias current suppressed


Gol’tsman APL 2001

100 nm wide wire, ~5 mm long

Single wire

Evolution of SNSPD design

Efficient optical coupling is a challenge:

Practical detection efficiency= coupling efficiency x intrinsic quantum efficiency

=> Increase active area

Verevkin APL 2002

Meander

100 nm wide wire, ~10 mm x 10 mm area



Next step:

Practical detection efficiency= coupling efficiency x intrinsic quantum efficiency

=> Boost absorption to increase intrinsic QE

Verevkin APL 2002

Meander

100 nm wide wire, ~10 mm x 10 mm area

Optical Cavity

nanowire

mirror

Light

substrate

Rosfjord OX 2006



Single wire MeanderIncrease coupling

Optical CavityIncrease absorption

Practical detection efficiency low

Max intrinsic efficiency ~20% at

1550 nm

Best reported intrinsic efficiency 57% at 1550 nm


Other developments in SNSPD designPhoton number resolution with spatial multiplexing (SINPHONIA, MIT)

Detector embedded in waveguide (MIT, Yale, TUe)

Dichovy et al Nature Photonics 2008 Dauler et al J. Modern Optics 2009

SNSPDs on Si substrates (Delft)

Dorenbos et al APL 2008 Hu IEEE Trans Appl. Supercon. 2009; Sprengers arXiv 1108.5107; Pernice arXiv 1108.5299


Superconducting nanowire single-photon detector system

•High efficiency SNSPDs from TU Delft Tanner et al Applied Physics Letters 96 221109 (2010)• 4 or more fiber-coupled SNSPDs can be implemented into a practical, closed-cycle refrigerator system Hadfield et al Optics Express 13 (26) 10864 (2005)

SNSPD system at Heriot-Watt


Superconducting nanowire single-photon detector system: practical performance

Tanner et al Applied Physics Letters 96 221109 (2010)


Quantum information science with single photons

• Quantum systems can be used to encode and manipulate information.• QIST promises dramatic improvements in secure communications

metrology, and computation.• In principle many candidate quantum systems (trapped ions, spins in

semiconductor quantum dots, superconducting circuits..)• Optical photon makes an ideal ‘flying qubit’• Photons have low decoherence even at room temperature, easy to route

and manipulate

|0 +|1e.g. polarization of photon

Superconducting single-photon photon detectors for

quantum information science

• Faithful detection of single photons is a key challenge.Hadfield Nature Photonics 3 (12) 696 (2009)

• Superconducting nanowire single-photon detectors (SSPDs or SNSPDs) have are an important emerging photon-counting technology.

• SNSPDs have an important role in new QIS applications:Characterization of quantum emittersQuantum Key Distribution (QKD)Operation of quantum waveguide circuits


Characterization of quantum emitters

Fiber

SSPD

Cryostat

Ti:SapphireLaser

Sample

Fast Photodiode

TAC/MCATiming Electronics

Stop

Start

Mono-chromator@ 935 nm

1 ps, 780 nm

BS

DichroicBSSample

InGaAs/GaAs QW, Room Temp

-500 0 500 1000 1500100

101

102

103

104

105

Time (ps)

Co

un

ts

ConventionalSi APD

FastSi APD

SSPD

-500 0 500 1000 1500100

101

102

103

104

105

Time (ps)

Co

un

ts

ConventionalSi APD

FastSi APD

SSPDInstrumentResponses

Decays

82 MHz

Stevens et al Applied Physics Letters 89 031109 (2006)

Quantum dot single-photon sources for quantum information science applications•Self-assembled quantum dots in III-V semiconductor are a promising source of single photons for optical QIS. Michler et al Nature 290 2282 (2001)•Single photon emission is verified by g(2)(0) measurement.•These measurements were on emitters at l ~900 nm; SNSPDs would also enable measurements on telecom wavelength single-photon sources

Hadfield et al Optics Express 13 10846 (2005)Hadfield et al Journal of Applied Physics 101 103104 (2007)

-500 0 500 1000 1500 2000 2500100

101

102

103

Fit: = 290 ps

Time (ps)

Co

un

ts

IRF DecayData

InGaAs grown on InPlDetect = 1650 nm

Long wavelength characterization of quantum emitters using SNSPDs

•Si single photon avalanche photodiodes do not work at l>1 mm.•SNSPDs can be used for characterization of long wavelength emitters.

• These measurements were carried out on semiconductor single-photon emitters; this technique would be equally applicable to studies of single photon emission from diamond defect centers, FLIM and FRET for single molecules and singlet oxygen detection.

Stevens et al Applied Physics Letters 89 031109 (2006)


Quantum Key Distribution(Bennett & Brassard, 1984)

Alice Bob

Eve

hn

R. Liechtenstein

•Quantum Key Distribution is a method for two parties (‘Alice’ and ‘Bob’) to create a ‘key’ for encrypting subsequent messages.

•Information encoded on single photons via phase or polarization

•Any attempted eavesdropping introduces errors and is therefore detectable.


Robert Hadfield - Heriot-Watt Quantum Photonics Workshop

• There are two contributions to the error rate (QBER):

QBER total = QBER interferometer + QBER dark counts

Dark count rate / Sifted bit rate

Distance

QB

ER 11 %

Log(K

ey R

ate

)

Distance

Sifted

Secret

Fixed ~1%

• Above a certain error rate (QBER) threshold, secure key can no longer be generated.

• As the transmission distance increases, the number of detected bits falls, so the error rate rises, causing the secret bit rate to eventually fall to zero.

Quantum Key Distribution – range limitations

Superconducting nanowire single-photon detectors in Quantum Key Distribution

Superconducting nanowire single-photon detectors: benefits for QKD in optical fibre:

- Single-photon sensitivity at 1550 nm

- Low dark counts

- Low timing jitter

- Gaussian instrument response function

=>Long distances

=>High bit rates


First QKD demonstration with SNSPDs in the DARPA quantum network

• A collaboration between NIST and BBN Technologies (Jonathan Habif, Chip Elliot) sponsored by the DARPA QuIST programme.• First prototype SNSPD system delivered to BBN end 2005.

Bob

Alice (behind)

SNSPD Closed-cycle system

Hadfield et al Applied Physics Letters 89 241199 (2006)

Clock rate 3.3 MHz

42.5 km spool

25 km spool

Link loss (dB)Bi

t rat

e (b

its/s

)

World record result for long distance QKD in optical fiber using SNSPDs

• Demonstration carried out end 2006 in Yamamoto lab, Stanford University (Stanford/NTT/NIST)

• 10 GHz clocked QKD system at l= 1550 nm using superconducting detectors

10 GHz

1 GHz

Takesue et al Nature Photonics 1 343 (2007)


New directions in QKD: ground to spaceVision of European Space Agency SpaceQUEST topical team (led by Prof. Anton Zeilinger, University of Vienna):

QKD from the International Space Station (ISS).

Photon flux

Microlens array

Cavity enhanced nanowire pixels

Role for SNSPDs?

R Ursin et al Europhysics News 40 (3) 26 2009


Quantum waveguide circuits

Optical waveguide circuits can be used to replace conventional optics.

Politi et al Science 320 5876 (2008)

Jeremy O’Brien, University of Bristol


CW laser, 402nm, 60mW

μm actuator

SNSPDs

Waveguide Circuit

BiBO

PMF

SMF

FilterTCSPC Card

a

b

cd

804nm photon pairs

with Jeremy O’Brien, University of Bristol, UK

Operating quantum waveguide circuits with SNSPDs


Operating quantum waveguide circuits with SNSPDs: initial experiments at l=805 nm

VSNSPD 92.3 %

Natarajan et al Applied Physics Letters 96 211101 (2010)

• First generation quantum waveguide circuits: silica on silicon waveguides, downconversion pair source at l=850 nm (as used in Politi et al Science 320 5876 (2008))•SNSPDs replace Si SPADs•Demonstrations:

-Two photon interference (Hong-Ou-Mandel dip)-Tuned two phonon interference with resistive phase shift-CNOT gate

F=90.4%


• First generation quantum waveguide circuits: silica on silicon waveguides, downconversion pair source at l=850 nm and Si SPAD detectors Politi et al Science 320 5876 (2008)

• A much wider range of high performance waveguide components (compact low loss waveguides, high speed switches and modulators)

• SNSPDs allow operation of next generation quantum waveguide circuits at 1550 nm.

• Recent reports show that SNSPDs can also be integrated on-chip with the waveguide. This is crucial for the scalabilty of circuits in demanding applications such as optical quantum computing.

Operating quantum waveguide circuits with SNSPDs: migrating to telecom wavelengths


Heralded source with fast lithium niobate switch

%1.09.97 Switching efficiency

MZI driven with a 4 ns rising time pulse

V

Bonneau et al Fast path and polarization manipulation of telecom wavelength single photons in lithium niobate waveguide devices arXiv 1107.3476 (2011)

Fast switching of quantum interference

a

b

c

d

Signal generator

Counting logic

C1 C2

Counting logic with toggle between two separate counters

11cos02202

sin11

Square waves 4MHz

q = 0 q =p/2SPDC

%282

%22

C2

C1

Bonneau et al Fast path and polarization manipulation of telecom wavelength single photons in lithium niobate waveguide devices arXiv 1107.3476 (2011)

Prospects and challenges for SNSPD development:• Achieving high efficiency at mid IR wavelengths• Reducing the timing jitter• Increasing the active area• Integrating devices on-chip with optical and electrical elements (optical

waveguide circuits, readout electronics)

Potential breakthroughs:• Large area single photon detectors/detector arrays with high efficiency,

picosecond timing resolution and gigahertz count rates from UV to mid IR wavelengths

• Adoption in new application areas: quantum communications and computing, LiDAR, astronomy, life sciences, integrated circuit testing

Infrared superconducting single-photon detectorsOutlook

Superconducting nanowire single-photon detectors (SNSPDs) offer very good practical performance at telecom wavelengths and have successfully been used in challenging quantum information science experiments.


Infrared superconducting single-photon detectors Robert Hadfield Heriot-Watt University, Edinburgh,...

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