2 research outputs found
Enhancing capacity of coherent optical information storage and transfer in a Bose-Einstein condensate
Coherent optical information storage capacity of an atomic Bose-Einstein
condensate is examined. Theory of slow light propagation in atomic clouds is
generalized to short pulse regime by taking into account group velocity
dispersion. It is shown that the number of stored pulses in the condensate can
be optimized for a particular coupling laser power, temperature and interatomic
interaction strength. Analytical results are derived for semi-ideal model of
the condensate using effective uniform density zone approximation. Detailed
numerical simulations are also performed. It is found that axial density
profile of the condensate protects the pulse against the group velocity
dispersion. Furthermore, taking into account finite radial size of the
condensate, multi-mode light propagation in atomic Bose-Einstein condensate is
investigated. The number of modes that can be supported by a condensate is
found. Single mode condition is determined as a function of experimentally
accessible parameters including trap size, temperature, condensate number
density and scattering length. Quantum coherent atom-light interaction schemes
are proposed for enhancing multi-mode light propagation effects.Comment: 12pages. Laser Physics, in pres
A photonic Carnot engine powered by a spin-star network
We propose a spin-star network, where a central spin- is coupled with
XXZ interaction to outer spin- particles, as a quantum fuel. If the
network is in thermal equilibrium with a cold bath, the central spin can have
an effective temperature larger than the bath one and scaling nonlinearly with
. The nonlinearity can be tuned to or with the anisotropy
parameter of the coupling. Using a stream of central-spin particles to pump a
micromaser cavity, we calculate the dynamics of the cavity field using a
coarse-grained master equation. Our study reveals that the central-spin beam
effectively acts as a hot reservoir to the cavity field and brings the field to
a thermal steady-state whose temperature benefits from the same nonlinear
enhancement with , and results in a highly efficient photonic Carnot engine.
The validity of our conclusions is tested against the presence of atomic and
cavity damping using a microscopic master equation method for typical microwave
cavity-QED parameters. An alternative equivalent scheme where the spin- is
coupled to a macroscopic spin- particle is also discussed.Comment: 7 pages, 4 figure