Mauro Rajteri
Divisione OTTICA
Mauro Rajteri, 12/06/2013 Panoramica INRIM
Photon: also called Light Quantum, minute energy packet of
electromagnetic radiation. The concept originated (1905) in
Einstein’s explanation of the photoelectric effect (enc. Brittanica)
Photon counting:
average count rate  intensity of the light beam
but
actual count rate fluctuates from measurement to measurement.
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Coherent light & constant intensity:
3.1
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"Classical" Single photon
detector

Photon source
Photon number resolving (PNR)
detector
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TES: a superconducting film operated in the temperature
region between the normal and the superconducting state
DTc ~ 1 mK  high sensitive thermometer
t (s)
Ibias
R
Ites
Workig Point
I
Tc ~ 100 mK
T
Rbias<< Rtes
DT DR @ Voltage bias  DI
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TES: a superconducting film operated in the temperature
region between the normal and the superconducting state
DTc ~ 1 mK  high sensitive thermometer
t (s)
Ibias
R
1 ph
Ites
Workig Point
I
Tc ~ 100 mK
T
Rbias<< Rtes
DT DR @ Voltage bias  DI
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TES: a superconducting film operated in the temperature
region between the normal and the superconducting state
DTc ~ 1 mK  high sensitive thermometer
2 phs
t (s)
Ibias
R
Ites
Working Point
I
Tc ~ 100 mK
T
Rbias<< Rtes
DT DR @ Voltage bias  DI
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Bilayer – proximity effect Ti=24 nm, Au=54 nm


Tc =121 mK
∆Tc = 2 mK
Rn = 0.220 Ω
10 µm X10 µm
20 µm X 20 µm
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Pinc
Pe
g= thermal conductance
Te
Superconductor - e
ge-ph
Ps
Superconductor - ph
Tph
K = constant: material and geometry
dependent
Tsub
n = constant: depends on the dominant
thermal coupling mechanism
gph-sub
Substrate
gsub-b
Thermal bath
n
Ps  K (T n  Tsub
)
Tb
For T < 1K  electron-phonon decoupling  n  5
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DE FWHM  2.355 4k BTc Esat
E sat 
n
2
CTc

Intrinsic Energy Resolution
∆EFWHM is proportional to the operating temperature Tc
n

   Ts
 etf   th 1  1  n
n  Tc







1
Effective TES response time
etf is lower than th if /n >1
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25 m
0
2w ~19÷
2
w
2w
z ~ 125
m
Gaussian beam:
w0=4.7/5.6 m @
l=1.3/1.55 m
(TES 20 x 20 m)
1,5 mm
1,5 mm
0,25
1mm
0,5 mm
5 mm
0,5 mm
0.8 mm
0,25
0,5 mm
back off
Silicon V-groove
with fiber array
acc ~ 58% @1.55m ÷ 80% @1.3m
Cu bracket
3 mm
Silicon
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Optical coupling fiber-TES
Reflection and transmission of superconducting film
 Antireflection coating or optical cavity
2 layers
Substrate
a-Si3N4:Hy (low reflection index)
a-SiH (high reflection index)
R(1550)=0.018%
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Laser
DITES
Electronics
& data
aquisition
Optical
fiber
Attenuator
INRIM: TES
module
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SQUID current
sensors (PTB)
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Noisy: ΔE = 0.46 eV
2000
1
histogram noisy
fit
1800
1600
(a)
occurrences
1400
1200
Wiener filter:
2x improvement on DE
2
1000
800
600
Wiener: ΔE = 0.22 eV
3
400
4
200
0
0
10
20
30
40
amplitude [mV]
3000
histogram Wiener
fit
5
50
2500
60
(b)
occurrences
2000
D. Alberto, et al, Optical Transition-Edge Sensors
Single Photon Pulse Analysis, IEEE Trans. Appl.
Supercond., 21 , 285 – 288 (2011)
1500
1000
500
0
0
10
20
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30
40
amplitude [mV]
50
60
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phs
20X20 μm2
l=1570 nm
L. Lolli, et al. J. Low Temp. Phys., vol. 167, pp. 803-808, 2012.
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Detector to be Calibrated
w
s
N2 = 2 N
N1 = 1 N
Klyshko
1 =NC/ N2
COUNTER
N1
NC
w
COINC
COUNTER
N
p
PARAMETRIC
CRYSTAL
w
i
NC= 1 2 N
Absolute
Quantum
Efficiency
N2
COUNTER
“Herald” Detector
Drawback: Klyshko's technique is not able to exploit the PNR ability of the
detector
Proposal and demonstration of an absolute technique for measuring
quantum efficiency, based on an heralded single photon source, but
exploiting the PNR ability of the detector
A. Avella et al OPTICS EXPRESS 2011 19 p. 23249-23257
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PH (i )
PA (i )
Probability of observing i photons per heralding count
in the presence of the heralded photon
Probability of observing i photons per heralding count
in the absence of the heralded photon
(i.e. of observing i “accidental” counts)
The probability of observing 0 photons per heralding count :
PH (0)   (1   ) PA (0)  (1   ) PA (0)
Non detection & No accidental
  
False her.& No accidental
“Total” Quantum Efficiency of the PNR detector optical
and coupling losses 
 detector proper Quantum Efficiency 

Probability of having a True Heralding Count
(not due to stray-light or dark counts)
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The probability of observing i photons per heralding count
PH (i)   [(1   ) PA (i)   PA (i 1)]  (1   ) PA (i)
From each PH (i ) a value of “Total” Quantum Efficiency
can be estimated  Consistency Test
From the probability of 0
From the probability of i
PA (0)  PH (0)
0 
 PA (0)
PH (i )  PA (i )
i 
 [ PA (i  1)  PA (i)]
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IF1
PDC single photon source
Pump source
HWP NLC
TES detection
system
IF2
b
a
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PUMP
total
quantum
efficiency
DET1
6 Repeated
measurements
each 5 hr. long
>5 106 counts
Heralded
Accidental
@ 807 nm
prob. of true
heralding counts
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POVM
provides the description of the measurement process
“n”
Prob. of output “n”
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POVM
provides the description of the measurement process
“n”
Prob. of output “n”
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POVM
provides the description of the measurement process
“n”
Prob. of output “n”
: Prob. of having output “n” with m photons as input
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Simplest Solution:
Fock state source
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Simplest Solution:
Fock state source
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Simplest Solution:
Fock state source
Affordable Solution: Coherent source
[Lundeen et al., Nat. Phys 5, 27 (2009)]
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Coherent source
Pulsed laser source
Experiment with a TES
1570 nm
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Coherent source
Pulsed laser source
Experiment with a TES
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Coherent source
Pulsed laser source
Experiment with a TES
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Coherent source
Linear detection model
  =5.1%
G. Brida
etRajteri,
al New
Journal of
Physics 14
(2012) 085001
Mauro
12/06/2013
Panoramica
INRIM
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Joint Projects for the exchange of researchers
within the Executive Programme Italy-Japan 2010-2012
Alignment:
ADR cold finger
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TiAu TES Tc=301 mK
73 phs
l=1535 nm
QE  50 %
@ 500 kHz means
3.65x106 photons/s (473 fW)
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Rn=0.45 
R(T , I ) 
Rn
2

 T  Tc   I 
1

tanh



D



2
n
n

 CeT  IR (T , I )  k (T  Ts )
 

LI  I bias Rs  I R p  Rs  R(T , I )

45nm Au+45nm Ti
10 m x 10 m
Tc=106 mK
Ce=0.35fJ/K

G  nkTcn1  44pW/K
  23
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eff = 3.8 s
DE = (0.113 ± 0.001) eV
DE  2 2 ln 2
 1 E
x2  x1
(Submitted to APL)
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TES  Photon number resolving detectors 
 Wavelength range: UV-IR 
 Quantum efficiency:50%90% 
 Dark counts: background limited 
 Count rate:  1 MHz 
 Working temperature: < 1K 
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Fabbricazione: C. Portesi, E. Monticone
Sviluppo 
Caratterizzazione : E. Taralli, L.Lolli , E. Monticone, M. Rajteri
(criogenica, elettrica e ottica)
E. Taralli, L. Callegaro (impedenza)
Taratura

Applicazioni
Ottica quantistica: A. Avella,G. Brida, L. Ciavarella, I.
Degiovanni, M. Genovese, M. Gramegna, M.G. Mingolla,F.
Piacentini, M.L. Rastello, P. Traina
Collaborazioni 
J. Beyer, D. Fukuda, T. Numata, M.G.A. Paris, M. White,
G. Cantatore, G. Ventura
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2001-2004
-Fotorivelatori superconduttivi ad elettroni caldi per il VIS-IR
-Realizzazione di STJ come rivelatori in regime di conteggio di fotoni per
applicazioni astrofisiche
E45 (2006-2010)
Rivelatori superconduttivi a transizione
di fase per conteggio di singoli fotoni
Quantum Candela (2008-2011)
Progetto premiale P5 (2012-2013)
Oltre I limiti classici della misura
NEW08 MetNEMS (2012-2015)
Metrology with/for NEMS
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