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MANIPULATING THE QUANTUM STATE
OF SINGLE ATOMS AND PHOTONS
works of Nobel Laureates in physics 2012
A.V.Masalov
Lebedev Physics Institute, RAS, Moscow
[email protected]
фото
Nobel Prize in Physics 2012:
Serge HAROCHE and David J. WINELAND
"FOR GROUND-BREAKING EXPERIMENTAL METHODS
THAT ENABLE MEASURING AND MANIPULATION
OF INDIVIDUAL QUANTUM SYSTEMS“
PHOTONS
IONS
Serge HAROCHE
École Normale Supérieure, Paris, France
MANIPULATING THE QUANTUM STATE
OF SINGLE PHOTONS
INDIVIDUAL QUANTUM SYSTEMS:
photons of electromagnetic field @ 51.1 ГГц ( ~ 6 mm);
number of photons – from 1 to about 10.
MEASURING AND MANIPULATION:
by means of single atoms in superpositional states.
SUPERCONDUCTING CAVITIES:
- Open Fabry Perot
- Niobium on diamond machined copper
- Unprecedented lifetime @ 51 GHz, 0.8 K :
Tc = 0,13 s
Q = 4,2 × 1010
F = 4,6 × 109
!!! Average number of thermal
photons ~ 0.05
CIRCULAR RYDBERG ATOMS:
- Long lifetime (30 ms)
- Millimeter-wave transitions
- Tunable via the Stark effect
- Large coupling to radiation
- Efficient and state-selective
single-atom detection
!!! Excitation to superpositional
n=3
n=2
n=1
n=0
states (by ‘’-pulse of light):
 g  e
B – atomic source (beam of single Rb atoms) selected by velositiy:
~ 900 pc/s, ~ 250 m/s.
С – superconducting resonator: 51.1 GHz, 0.8 K, tunable (!)
R1 и R2 – auxilary resonator for excitation anf analysis of atoms.
S – source of radiation at about 51 GHz.
D – detector of atomic state: g or e .
Source R1  ‘’-pulse  atom  g   e
Main resonator C tuned close but out of resonance with atoms
Atoms are exposed to Stark-shift of levels in the interaction area C:
Atom + 1 photon:
Source R2  ‘’-pulse 
 g  e 
 g  ei  e
atom + 1 photon ei   1 pure exited state!
atom + 0 photon
INTERFEROMETER RAMSEY
  0 pure ground state!
SINGLE PHOTON IN RESONATOR
Photon decay in resonator:
1 realization
5 realizations
15 realizations
904 realizations
INTERFEROMETER RAMSEY
The ‘door’ from classical world to quantum one:
‘’-pulse
The ‘door’ from quantum world to classical one:
interferometer Ramsey
 g  e
 g  e
g
e
More delicate coding of photon numbers in resonator
by phase in superpositional state of atoms
Number of
photons
Atomic state
  2 /8
Atomic state out of
Ramsey interferometer
0
0  g  ei 0 e
g  0  e 1
1
0  g  ei1 e
g sin   e cos
2
0  g  ei 2 e
g sin 2  e cos 2
3
0  g  ei 3 e
g sin3  e cos3
4
0  g  ei 4 e
g sin 4  e cos 4
5
0  g  ei 5 e
g sin5  e cos5
6
0  g  ei 6 e
g sin 6  e cos6
7
0  g  ei 7 e
g sin 7  e cos7
More delicate coding of photon numbers in C
by phase in superpositional state of atoms
1. Photon-state preparation in C by resonant atoms.
2. Photon-state detection by non-resonant atoms:
QUANTUM NON-DEMOLITION MEASUREMENTS
OF PHOTON NUMBER IN RESONATOR
POISSON DISTRIBUTION OF PHOTONS
(at final stage on measurements)
TRACING THE NUMBER OF PHOTONS IN RESONATOR
Homodyning the quantum state of photons
Reconstruction of density-matrix and quasiprobability distribution
of radiation with n = 1
Reconstruction of density-matrix and quasiprobability distribution
of radiation with n = 2
Reconstruction of density-matrix and quasiprobability distribution
of radiation with n = 3
Reconstruction of density-matrix and quasiprobability distribution
of radiation with n = 4
Reconstruction of density-matrix and quasiprobability distribution
of radiation in the states of ‘Schredinger-cat’
even
odd
decoherence
END
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