27 research outputs found
Quantum Memory for Photons in Case of Many Close Lying Exciton Resonances in Solids
The possibility of storage of quantum information with photons is studied in
the case of resonant transitions via many close lying exciton levels in a solid
with impurity Lambda-atoms. The upper levels of the impurity atom form resonant
Fano states, similar to the autoionization atomic states, due to the
configuration interaction with the continuum of the exciton band. In this case
slowing of light pulses is shown to be realistic, in the presence of the
control field, down to the group velocity much lower than that in vacuum. The
possibility of storage and reconstruction of a quantum pulse is studied in the
case of the instantaneous switching on/off of the control field. It is shown
that the signal quantum pulse cannot be stored undistorted for differing values
of Fano parameters and for non-zero two-photon detuning and decay rate between
the lower levels (decoherence). However, for small difference of the Fano
parameters and for small values of the two-photon detuning and the decoherence
there is no distortion in the case where the length of the pulse is much longer
than the linear absorption (amplification) length, so the shape and quantum
state of the light pulse can be restored.Comment: 15 pages, 3 figure
Collision of two atoms in laser radiation field with formation of Feshbach resonances
Based on the simplest two-channel model we theoretically consider laser induced elastic
and inelastic collision of two atoms with formation of Feshbach resonance. In cases of
one- and two-photon resonances of laser radiation with two discrete vibrational molecular
levels, we show that Feshbach resonances appear at interaction of external magnetic field
with dressed states formed via Autler-Townes effect. We also study the laser-induced
inelastic collision and its influence on the considered processes. In case of two-photon
resonance between discrete vibrational molecular states the Feshbach resonances arise
under action of magnetic field via Autler-Townes effect, while the laser-induced
transition into the elastic-channel continuum is in this case absent. We obtain the
cross-sections of elastic and inelastic scattering and show that quenching of resonance
occurs under certain conditions. The obtained results can be employed in new studies of
collisions of atoms, e.g., of alkali metal atoms, and for interpretation of new
experiments in BECs