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Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology,
Cambridge, Massachusetts 02139, USA
Superconducting Nanowire Single-Photon Detectors
K. K. Berggren
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http://messenger.jhuapl.edu/news_room
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3
Free-Space Optical Communications
receiver 109 km
Boroson, Biswas, Edwards, "Overview of NASA's mars laser communications demonstration system," FREE-SPACE LASER COMM. TECH. XVI 5338: 16-28, 2004
Toyoshima, et. al., “Comparison of microwave and light wave communication systems in space applications,” Opt. Eng. 46 015003 (2007)
transmitter
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Free-Space Optical Communications
0000
0001
time
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
hv hv
Encodes 01011001 (4 bits/photon)
receiver 109 km
Boroson, Biswas, Edwards, "Overview of NASA's mars laser communications demonstration system," FREE-SPACE LASER COMM. TECH. XVI 5338: 16-28, 2004
Toyoshima, et. al., “Comparison of microwave and light wave communication systems in space applications,” Opt. Eng. 46 015003 (2007)
transmitter
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Photons
• Illumination in eye from 1 pixel of laptop at 100 km in 1 sec
• Energy inversely proportional to wavelength
– Longer wavelength => harder to detect
5
Berggren
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Superconductive Nanowire Single-Photon Detector
6
Superconductive Nanowire
Single-Photon Detector
90 nm
3 µm
proximity-effect-correction features
electrode
electrode
Gol’tsman et al., APL, (2001).
Yang et al., IEEE TAS (2005)
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lens
cornea
retina
optic
nerve
vitreous
humor
Eye Anatomy
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lens
cornea
retina
optic
nerve
vitreous
humor
sapphire
substrate
antireflection
coating
cavity
NbN
mirror contact pad
light
Eye Anatomy
sapphire niobium
nitride
gold….
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Tapetum Lucidum of a Cat
9
Berggren
Bernstein and Pease, “Electron Microscopy of the Tapetum Lucidum of
the Cat” Journal of Cell Biology, Vol. 5, 35-39, (1959)
~ 100 nm
retina
tapetum
lucidum
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lens
cornea
retina
optic
nerve
vitreous
humor
sapphire
substrate
antireflection
coating
cavity
NbN
mirror contact pad
light
Eye Anatomy
tapetum
lucidum
sapphire niobium
nitride
gold….
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Characteristics of Photon Detectors
• Efficiency
• Reset time
• Jitter
• Dark count rate
11
time
hν incident photons
with no signal
time
incident photons
blocked by
earlier signal
time t1 t3
varying delay between
photons and signals
voltage
time
voltage pulses with no
corresponding photon
t2
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Nanowire Single-Photon Detector
superconducting nanowire
single-photon detector
photomultiplier tube
avalanche photodiode
transition edge sensor
104
104 100
1 / jitter
[MHz]
1 / reset time
[MHz] device
efficiency
[%]
• VLSI device evaluation
• LIDAR
• Communication
– quantum
– interplanetary
APPLICATIONS
Comparison at 1.55 µm
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Device Operation
DEVICE OPERATION
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Superconductive Nanowire Behavior
I
V
critical current, Ic
Berggren
superconducting
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< 100 nm
niobium nitride
Detection Mechanism
Explanation
4 nm
superconductor is biased near its transition
detector
Ibias
Rload
L
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Detection Mechanism
Explanation
photon-induced hotspot forces bias current above critical density
< 100 nm
niobium nitride 4 nm
detector
Ibias
Rload
L A. D. Semenov, G. N. Gol’tsman, and A. A. Korneev, “Quantum detection by current carrying superconducting film,” Physica C, vol. 351, pp. 349–356, 2001.
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Detection Mechanism
Explanation
resistive barrier spans nanowire
< 100 nm
niobium nitride 4 nm
detector
Ibias
Rload
L
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Detection Mechanism
Explanation
4 nm
< 100 nm
niobium nitride
resistance grows from heating
detector
Ibias
Rload
L
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Detection Mechanism
Explanation
4 nm
< 100 nm
niobium nitride
current is diverted
detector
Ibias
Rload
L
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< 100 nm
niobium nitride
Detection Mechanism
Explanation
4 nm
superconductivity is restored
detector
Ibias
Rload
L
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< 100 nm
niobium nitride
Detection Mechanism Explanation
4 nm
superconductivity is restored
detector
Ibias
Rload
L
21
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< 100 nm
niobium nitride
Detection Mechanism
Explanation
4 nm
bias current is restored
detector Rload
L
Ibias
Kerman, Dauler, Keicher, Yang, KB, Gol'tsman, Voronov, Applied Physics Letters, (2006)
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Cross-section transmission-electron
micrograph
90 nm
sapphire
cavity dielectric
Au mirror
NbN
24 Rosfjord et al., Opt. Express (2006)
sapphire fib
er
gold
~λ/4
anti-reflection
coating
NbN
SNSPD integrated in an optical cavity
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Summary of Device Performance
25
1 ps, 1550 nm
optical pulse
28.5 ps FWHM
-100 -80 -60 -40 -20 0 20 40 60 80
0.01
0.1
1
No
rma
lize
d C
ou
nts
(a
.u.)
Time (ps)
Time (ns)
Voltage (mV)
3 ns
Kerman et al. in APL (2006)
Background Counts
~100 s-1
(97.5% bias, 2.7K)
70-nm-wide detector, 140-nm pitch
210-nm-thick cavity
0
0.4
0.8
0 0.5 1
~ 65 %
~ 70 %
Dete
ctio
n e
ffic
iency
bias current / Ic
Collaboration with
Lincoln Laboratory
Time (ps)
Norm
aliz
ed C
ou
nts
(a.
u.)
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Fabrication
FABRICATION
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Basic Fabrication Flow hydrogen silsesquioxane (HSQ)
(electron-beam resist)
gold contact pads
sapphire substrate
niobium nitride (from collaborators)
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Basic Fabrication Flow
niobium nitride nanowire
hydrogen silsesquioxane (HSQ)
(electron-beam resist)
gold contact pads
sapphire substrate
niobium nitride (from collaborators)
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Basic Fabrication Flow
HSQ
anti-reflection coating
niobium nitride nanowire
hydrogen silsesquioxane (HSQ)
(electron-beam resist)
gold contact pads
sapphire substrate
niobium nitride (from collaborators)
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Cavity Fabrication Flow
HSQ
Au contact pads
sapphire substrate NbN
detector
1nm/
120nm
Ti/Au
mirror
HSQ cavity
HSQ
ARC
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Photon Statistics
APPLICATION
31
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10 µm
32
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Pseudo-Thermal Source Setup
Ground
Glass
4-element
SNSPD
Cryostat
Fiber
12 V DC Fan (up to 6000 rpm)
Grating-Stabilized
CW Diode Laser
1070 nm
Scattered Light
Speckle
PC
6-channel
FPGA
Time-stamp each channel
~7 ns bins
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3-photon coincidences
t1
t2
2-photon coincidence conditions:
t1 = 0
t2 = 0
t1 = t2
3-photon coincidence :
t1 = t2 = 0
t
34
10 µm
Ele
ment
1
Ele
ment
2
Ele
ment
3
Ele
ment
4
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3rd-order Intensity Correlations
“High-order temporal coherences ofchaotic and laser light”, Stevens, Baek, Dauler, Kerman, Molnar, Hamilton, Berggren, Mirin, and Nam, Optics Express, 18, 1430 (2010)
g(3)(0,0) = 5.87 ~ 3!
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Photon Statistics
NANO-ANTENNAE
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The Three Keys to Efficiency
active
area
coupling
efficiency absorptance
v
resistive state
formation
r
t
× × ×
37
v
threshold
detection
× ×
v
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Antenna – Integrated Detector
small pitch
top view
cross section
large pitch fill the gap with gold
v
t
v
t
v
t
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Optical Nano-Antenna
Au … …
TM
k
NbN
39
Final Version
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Optical Nano-Antenna
Au … …
TM
k
NbN
40
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Fabrication
ion-beam cross-section
fabrication challenges
• e-beam writing on thick HSQ
• gold migration in evaporation
sapphire
Au
Pt
HSQ
Au
600 nm
80 nm
9 mm
Au
pad
Au
pad
SiO2/
Ti/Au
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• Nano-antennae improve collection, permitting 3 x area, with same reset time
Nano-Optical Antenna for Nanowire Detectors
• 600-nm pitch, 9-mm-by-9-mm area
• 47% device efficiency • 5 ns reset time
Hu et. al. Optics Express, 2010
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Photon Statistics
SUB-30-NM DEVICES
43
80 nm
60 nm 40 nm 30 nm
20 nm 10 nm
44
80 nm
60 nm 40 nm 30 nm
20 nm 10 nm
45
80 nm
60 nm 40 nm 30 nm
20 nm 10 nm
46
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30 nm
1 µm
30-nm-wide-nanowire SNSPD
47
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w = 90 nm
Standard vs Ultranarrow-Nanowire SNSPDs
Constrictions
48
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constricted
constriction-free
more constricted
Standard vs Ultranarrow-Nanowire SNSPDs
Constrictions
49
w = 90 nm
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constriction-free
w = 30 nm
Standard vs Ultranarrow-Nanowire SNSPDs
Constrictions
50
w = 90 nm
constricted
more constricted
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constriction-free
w = 30 nm
Standard vs Ultranarrow-Nanowire SNSPDs
Constrictions
51
w = 90 nm
constricted
more constricted
A. D. Semenov, G. N. Gol’tsman, and A. A. Korneev, “Quantum detection by current carrying superconducting film,” Physica C, vol. 351, pp. 349–356, 2001.
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constriction-free
w = 30 nm
Standard vs Ultranarrow-Nanowire SNSPDs
Constrictions
52
w = 90 nm
constricted
more constricted
A. D. Semenov, G. N. Gol’tsman, and A. A. Korneev, “Quantum detection by current carrying superconducting film,” Physica C, vol. 351, pp. 349–356, 2001.
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constriction-free
constriction-free
w = 30 nm
Standard vs Ultranarrow-Nanowire SNSPDs
Constrictions
53
w = 90 nm
constricted
more constricted
constricted
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Negligible responsivity above 2 μm
w = 90 nm
54
Standard vs Ultranarrow-Nanowire SNSPDs
Gol’tsman et al., IEEE Trans. Appl. Supercond (2011)
w = 55 nm
w = 100 nm
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Negligible responsivity above 2 μm
w = 90 nm
55
Standard vs Ultranarrow-Nanowire SNSPDs
Gol’tsman et al., IEEE Trans. Appl. Supercond (2011)
w = 55 nm
w = 100 nm
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λ = 0.5 μm
w = 85 nm
56
Detection efficiency vs IB and wavelength
λ = 2 μm
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λ = 0.5 μm
w = 30 nm
57
λ = 2 μm
Detection efficiency vs IB and wavelength
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0
3.6
7.2
η (%)
w = 85 nm
w = 50 nm
w = 30 nm
Detection efficiency vs IB, wavelength and width
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Fabrication
SIGNAL TO NOISE RATIO
59
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Low signal to noise ratio
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Low signal to noise ratio
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“A Cascade Switching Superconducting Single Photon Detector,”
M. Ejrnaes, R. Cristiano, O. Quaranta, S. Pagano, A. Gaggero, F.
Mattioli, R. Leoni, B. Voronov, and G. Gol'tsman,
Appl. Phys. Lett. 91, 262509 (2007)
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Superconducting Nanowire Avalanche Photodetectors
(SNAPs)
63
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Superconducting Nanowire Avalanche Photodetectors
(SNAPs)
1.4 µm
30 nm
64
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IB RA
VO
UT
+
- Basic model of SNAP operation
65
LS
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IB RA
VO
UT
+
- Basic model of SNAP operation
66
LS
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IB RA
VO
UT
+
- Basic model of SNAP operation
67
LS
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IB RA
VO
UT
+
- Basic model of SNAP operation
68
LS
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SNAPs improve the SNR
4-SNAP
3-SNAP
2-SNAP
SNSPD
69
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Experimental results
λ = 1550 nm
SNSPD
2-SNAP
70
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Experimental results
λ = 1550 nm
SNSPD
2-SNAP
71
threshold current
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Experimental results
λ = 1550 nm
3-SNAP
SNSPD
2-SNAP
72
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Experimental results
λ = 1550 nm
3-SNAP
SNSPD
2-SNAP
73
In which bias range are 3-SNAPs working as single-photon detectors?
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IB RA
VO
UT
+
- SNAP operation below the avalanche current
74
LS
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IB RA
VO
UT
+
-
75
LS
arm
SNAP operation below the avalanche current
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IB RA
VO
UT
+
-
76
LS
SNAP operation below the avalanche current
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IB RA
VO
UT
+
-
77
LS
SNAP operation below the avalanche current
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IB RA
VO
UT
+
-
78
LS
trigger
SNAP operation below the avalanche current
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IB RA
VO
UT
+
-
79
LS
SNAP operation below the avalanche current
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IB RA
VO
UT
+
-
80
LS
SNAP operation below the avalanche current
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IB RA
VO
UT
+
-
81
LS
SNAP operation below the avalanche current
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IB RA
VO
UT
+
-
82
LS
SNAP operation below the avalanche current
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Experimental results
λ = 1550 nm
3-SNAP
SNSPD
2-SNAP
83
threshold current
avalanche arm-trigger
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increasing
power
IAV
η Power Dependence Explained
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η Power Dependence Explained
85
photon arm +
photon trigger
photon arm +
dark count trigger
IAV
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Electro-thermal simulation of SNAPs
86
initiating
secondary
Iout
avalanche superconducting
initiating:
secondary:
normal / superconducting boundary
photon
n
s
n
s
J. Yang et al. IEEE TAS (2007)
F. Marsili et al., APL (2011)
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3-SNAP in “arm-trigger” regime
87
Pseudo 2-SNAP
trigger
superconducting
I3
I2
I1
Iout
arm
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Inter-arrival time measurements
time
hν voltage
Avalanche mode:
88
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Inter-arrival time measurements
time
hν voltage
Avalanche mode:
tD1 tD2 tD3 tD4
τΦ1 τΦ2 τΦ3 τΦ4
89
Dt
f t f tt
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Inter-arrival time measurements
time
T voltage
Arm-trigger mode:
A T A T
90
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Inter-arrival time measurements
time
T voltage tD1 tD2
Arm-trigger mode:
A T A T
t2Φ1 t2Φ2
91
D 2t
f t f tt
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Inter-arrival time histograms
92
IB < IAV
IB > IAV
F. Marsili et al., Nanolett. (2011)
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20-nm-wide-nanowire SNAPs
20 nm
1.1 µm
93
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20-nm-nanowire-width SNAPs
2-SNAP
4-SNAP
3-SNAP
94
λ = 1550 nm
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The Future
• Scaling sensitivity out to longer wavelengths
– (is high-efficiency single-photon detection possible at 10 um?)
• Understanding the source of jitter
– Intrinsic to material? Electronic? Thermal? Electro-thermal?
– Dependent on design/architecture? Engineerable?
• Can we break the 1 ns speed limit?
– Need to investigate new materials
– Need to investigate new device designs
• Is near-100% efficiency possible?
95
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NbN-LL-171-A: 05-4-1
W=11 p=100
10 nm
1.1 µm
96
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Acknowledgements
MIT Quantum Nanostructures and
Nanofabrication Group
Vikas Anant (now at PhotonSpot)
Francesco Bellei
Andrew Dane
Eric Dauler (Lincoln Lab Fellow, now at
Lincoln Laboratory)
Charles Herder (undergraduate)
Xiaolong Hu (now at U. of Michigan)
Hasan Korre
Francesco Marsilli (post-doc, now at
NIST)
Faraz Najafi
Kristen Sunter
Joel Yang (ASTAR Fellowship, now at
A*STAR)
MIT Lincoln Laboratory
Eric Dauler
Andrew J. Kerman
Richard Molnar
Bryan Robinson
Scott Hamilton
NIST Martin J. Stevens Burm Baek Sae Woo Nam Richard P. Mirin
Other Collaborators
M. Csete (U. of Szeged)
Boris Voronov (MSPU)
Gregory Gol’tsman (MSPU)
Sponsors
AFOSR, IARPA, DARPA, NASA, NSF
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Photon Statistics
END OF PRESENTATION
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