Spectral density matrix of a single photon measured

1
Spectral density matrix of a single photon
measured

• Wojciech Wasilewski, Piotr Kolenderski, Robert
  Frankowski
• National Laboratory of Atomic, Molecular and
  Optical Physics, Torun

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Agenda

• Motivation

• Wave function

• Density matrix

• Results

• HOM interference

• Setup

• Projection

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Motivation

• Fundamental

• Applications

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Single photon WF
1?k
1?c Sck
Ec(x,t) Sck exp(ik.x-iwt)
?
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Single photon mixed
r Spa 1a??1a
1? Sck 1?k
r(t,t) Spa Ea(t) Ea(t)
E(x) Sck exp(ik.x-iwt)
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Hong-Ou-Mandel
?
? - ?
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Houng-Ou-Mandel
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Multisided observation
r(t,t) ?
f(t)
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Biased observation
f(t)
t
10
Double pulse
t
f(t)
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Phase
b
b
t
f(t)
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Phase space
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Projection onto cats state
?
?
?
?
14
Experimental scheme
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Simulated result
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Fourier transform
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Retrieval
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Setup
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Setup
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Reference
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Reference pulses
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Result r(l,l)
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Theoretical model (PK)
w1,k1??
w1w2, k1k2
w2,k2??
?w1,k1?,w2 ,k2?out?
sin(Dk L/2)/Dk
Ap(w1w2,k1k2)
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Mixedness
r(w,w) Spa 1a??1a
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Summary

• Real photons have some shape
• Or even a few eigenshapes with nonzero
  probabilities
• First full temporal characterization of a single
  photon
• Result agrees with the model

WW, P. Kolenderski, R. Frankowski quant-ph/0702200
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Sponsors

• EU under QAP project
• Fundation for Polish Science
• National AMO Lab
• MNiSW
• Regional grants