Transcript Заголовок слайда отсутствует

Strong light-matter coupling:
coherent parametric interactions in a cavity and free space
V. S. Egorov1, V. N. Lebedev1, I. B. Mekhov1,
P. V. Moroshkin2, I. A. Chekhonin1, and S. N. Bagayev3
1St.
Petersburg State University, V.A. Fock Institute of Physics, St. Petersburg, Russia
2Universite de Fribourg, Fribourg, Switzerland
3Institute of Laser Physics, Siberian Branch of RAS, Novosibirsk, Russia
The report is focused on
• Coherent interaction between an optically dense resonant medium and
near-resonant laser light
• Influence of intrinsic light-matter dynamics on nonlinear parametric
processes
• Role of the dispersion of a strongly coupled light-matter system
(polaritons)
• Peculiarities of the strong-coupling regime in a free-space in contrast to
cavity interactions
Strong-coupling regime of light-matter interaction
Two coupled oscillators: field and polarization of a medium
I. Energy exchange is faster than decoherence
High coupling coefficient, small relaxation
(dynamical effects may be significant)
Coherence of both field and matter is important
(adiabatic elimination cannot be applied)
II. Weak external field
Key role of reemission (reaction) field
(constant-field approximation does not work)
External field does not destroy collective behavior of an atomic ensemble
(beyond the framework of a single-atom model,
in contrast to Rabi flopping, Mollow-Boyd, and other strong-field effects)
Photons and matter excitations are presented by nearly equal
contributions (polaritons)
Strong-coupling regime has attracted attention in
Atomic and molecular optics
Dicke superradiance
(oscillatory regime)
Cavity QED
(up to single atom / photon interactions)
Solid-state optics
Exciton-polaritons
in semiconductor microcavities
with nanostructures
(single and multiple QWs and QDs)
- Stimulated scattering
- Parametric interactions
- Squeezing, entanglement
- Bose-Einstein condensation
It is important for quantum information processing with both
discrete and continuous variables
Interactions in a cavity
Spatial spectrum is fixed by a cavity
4
3
wr( k ) / wc
Splitting of a cavity mode
(collective vacuum Rabi oscillations)
2
1
0
-1
-2
-3
-4
-4
-3
-2
-1
0
ck / wc
1
2
3
4
Polariton dispersion in a cavity
Quantum beats in a two-level medium
“Spectrum condensation” in active systems
Weak coupling:
Saturated absorption line
Narrow-band
absorbing medium
Pumping
Broadband gain
medium
Strong coupling:
Bright doublet
Spectrum condensation of a multimode dye laser
with an intracavity absorbing cell (Ne discharge)
Strong-coupling regime in a free space
Spectrum
Short broadband pulse
Time
Spatial spectrum is NOT fixed by a cavity
(continuos)
Under linear interactions, frequency spectrum is entirely determined by
the input spectrum
No coherent density-dependent features in the output spectrum
(in contrast to vacuum Rabi oscillations in a cavity)
Coherent collective oscillations in temporal evolution
Possibility to observe collective features in
nonlinear parametric interactions
Nonlinear pump-probe interaction
Bloch equations:
pump
D+2
D+1
D0
probe
Pump
Two intersected pulses:
Nonlinear interaction:
Probe
Coupled Maxwell-Bloch
system
p+2
p-1
D-1
Collective optical ringing in an extended medium
Strong coupling condition:
frequency:
Propagation of a probe pulse in the presence of a pump
Coherent density- and coordinatedependent features under nonlinear
parametric interaction
Experiments in a Ne discharge
(588.2 nm)
Resonant atom density is
n=1013 cm-3
Transition from strong-coupling
to strong-field regime
Conclusions
Nonstationary interaction of laser pulses with a dense resonant medium was
considered under the strong-coupling regime of light-matter interaction
Internal collective light-matter dynamics was shown to significantly affect
nonlinear parametric interactions between short laser pulses
Efficient parametric processes in the strong coupling regime were proved even
for the free-space conditions
Contrary to stationary strong-field effects, the density- and coordinate-dependent
transmission spectra of the probe manifest the importance of collective
oscillations and cannot be obtained in the framework of a single-atom model
References
S.N. Bagayev, V.S. Egorov, I.B. Mekhov, P.V. Moroshkin, I.A. Chekhonin,
E.M. Davliatchine, and E. Kindel, Phys. Rev. A 68, 043812 (2003)
V.S. Egorov, V.N. Lebedev, I.B. Mekhov, P.V. Moroshkin, I.A. Chekhonin,
and S.N. Bagayev, Phys. Rev. A 69, 033804 (2004)