10 - Onera

Detecting single
photons
Andrea Fiore

Why single-photon
detectors?
Measure "very efficient" nonlinear frequency conversion...
A PhD student "under Rosencher's rule":
Wikipedia
Will I ever get a
few photons
and my thesis?
Solution n. 1: Change field and work on lasers...
Andrea Fiore

Single-photons again...
"Les photons ... présentent un certain nombre de comportements paradoxaux"
Emmanuel Rosencher, Optoélectronique, Masson ed.
"We estimate the potential market for Quantum Cryptography is
likely to reach $1 billion per annum"
Bob Gelfond, MagiQ Corporation, New York
id201 Singlephoton
APD
Presently limits
system performance
Let's get this fixed for good: Single-photon detectors
Andrea Fiore

t
3-10nm
Nanowire Superconducting
Single-Photon Detector
NbN
T>T C
I~I C
Golts'man et al., APL (2001)
+ V -
R hs
J>J C
w
60-100nm
Andrea Fiore

5μm
Meander SSPDs
5μm
Nanofabrication: CNR-IFN Rome
100nm
150nm
Marsili et al., Optics Express 2008
Andrea Fiore

+
V
-
Bias T
i
SSPD operation
Voltage (a.u.)
0
1.6 ns
-1
-10 0 10 20
Time(ns)
• 1000x more sensitive than InGaAs APDs at 1300-1500 nm
• Can run in continuous mode, with counting rates>80 MHz
• Timing resolution

Photon-number-resolving
detectors
Meander SSPDs do not resolve the photon number
+
V
-
Time
Bias T
?
i
Light Voltage
Rhs Rhs Single-φ PNR
det.
R L
Time
PNR functionality
needed in many
quantum protocols
Andrea Fiore

+
V
-
Parallel-Nanowire Detector
Bias T
Output pulse ∝ photon number if:
• N. wires >> N. photons
• Other wires do no shunt switching wire
Andrea Fiore

R L
V b
+
-
I
R hs
L kin
R 0
Electrical equivalent
circuit
S l
S l
R hs
I b
L kin
R 0
Sl Sl R hs
L kin
Sl Sl R hs
L kin
S l
I b I b I b
R 0
R 0
R A
+
V OUT
-
Andrea Fiore

Fabricated PNDs
R
Film growth and meas. @ EPFL,
nanofab. @CNR-IFN
R
Andrea Fiore

Experimental PND output
PND output voltage under
illumination with laser pulses:
Experimental I out (a.u.)
5
4
3
2
1
0
0 50 100 150
Time (ns)
Divochiy et al., Nature Photonics, 2008
Simulation:
Andrea Fiore

Voltage
Proving the PNR
functionality
Pulse height statistics with a sampling scope:
4 wires PND-R
66 nW
Most promising technology for fast and
sensitive PNR detection in the telecom range
Time
Detected pulses follow Poissonian statistics ⇒ Proof of PNR operation
Divochiy et al., Nature Photonics, 2008
Collaboration with MSPU
Andrea Fiore

Curiosity-driven: A singlephoton
nanodetector?
Detection mechanism in SSPDs is nanoscale,
but meander SSPDs usually cover large areas
⇒ We lose spatial information
Near-field imaging
Det.
• Direct detection in near-field
• Smaller detector ⇒ Lower noise
≈30 nm
Sub-λ quantum imaging
D'Angelo et al., Phys. Rev. Andrea Lett. 2001 Fiore

Nanoscale single-φ
detector
≈50 nm
QE
< 30 nm active
area possible
Andrea Fiore

10 -3 10 5
10 -2
n-SSPD performance
Proof of single-φ detection:
Counts (s -1 )
10 7
10 6
I b =8.5μA
50 nm
10 -1
Slope=0.99
Data
Linear fit
Light power (a. u.)
10 0
Diffraction spot of
microscope objective:
Bitauld et al., Nano Lett. 2010
•Able to image submicrometer (down to 500 nm) features
with single-photon sensitivity
•Expected detector resolution ≈50-100 nm
Andrea Fiore

Nanoscale PNR?
High bias current: Single-φ response
Andrea Fiore

Count rate (s -1 )
10 7
10 6
10 5
Nanoscale PNR detection
I =17μA
b s=1.9
I =14.4μA
b
Low bias current: s=2.98 (≥n)-photon detector
I =11.2μA
b
s=3.99
I =9.2μA
b
10 4
10 3
10 2
10 0
C∝
10 1
n
s=1.03
s
10 2
10 3
10 4
Average n. photons/pulse
Linear Fits
Andrea Fiore

Detection prob.
1,2
1
0,8
0,6
0,4
0,2
Multiphoton imaging
N=1
N=2
N=3
N=4
0
-3 -2 -1 0 1 2 3
Position (μm)
FWHM (μm)
N=1: FWHM=0.9 μm
N=4: FWHM=0.41 μm
1
0.8
0.6
0.4
FWHM
S = -0.53
1 2 3 4
• Increased contrast
Bitauld et al., Nano Lett. 2010
• Increased resolution possible with entangled light
N
∝
1
N
Andrea Fiore

Summary
Photodetection in superconducting nanowires opens new
avenues in single- and multi-photon detection
• PNRs detection possible at telecom wavelengths
• Nanoscale detection opens the way to nanoscale quantum
photonics
• Integration with GaAs-based (quantum) photonics possible
Andrea Fiore

Acknowledgements
Contributors:
- F. Marsili, D. Bitauld, S. Jahanmiri Nejad, J.P. Sprengers,
D. Sahin, G.J. Hamhuis, R. Notzel (TU Eindhoven)
- A. Gaggero, R. Leoni, F. Mattioli (CNR Rome, Italy)
- F. Lévy, R. Sanjines (EPF Lausanne)
Funding: EU-FP6 SINPHONIA and FP7 QUANTIP
Dutch STW-Vici, Swiss NCCR Quantum Photonics
Andrea Fiore