232 research outputs found
What is the reference frame of an accelerated observer?
The general construction of extended refrence frames for noninertial
observers in flat space is studied. It is shown that, if the observer moves
inertially before and after an arbitrary acceleration and rotation, the region
where reference frames can coincide with an inertial system is bounded for
final velocities exceeding 0.6 c.Comment: 5 pages, 2 figures, published in Phys. Lett. A 215, 1 (1996
Quantum Theory of a Bose-Einstein Condensate out of Equilibrium
We consider the interaction between a single-mode quantized perturbing
external field and a Bose-Einstein condensate (BEC) out of equilibrium. The
usual Rabi type oscillations between the ground and the excited state of the
coherent topological modes are observed with a Rabi frequency modified by the
two-body atomic interactions. Taking into account the granular structure of the
external perturbing field reveals the well know phenomena of collapse and
revival of the Rabi oscillations. In particular we find that atomic
interactions reduce the Rabi frequency and also affect the collapse and revival
sequence.Comment: Accepted for publication in Optics communicatio
Spontaneous emission of polaritons from a Bose-Einstein condensate
We study the spontaneous emission of a partially excited Bose-Einstein
condensate composed of two-level atoms. The formation of polaritons induced by
the ground-state part of the condensate leads to an avoided crossing in the
photon spectrum. This avoided crossing acts similarly to a photonic band gap
and modifies the spontaneous emission rate.Comment: 4 pages, 2 figures, revte
Decoherence of Atomic Gases in Largely Detuned Laser Fields
We study theoretically the decoherence of a gas of bosonic atoms induced by
the interaction with a largely detuned laser beam. It is shown that for a
standing laser beam decoherence coincides with the single-particle result. For
a running laser beam many-particle effects lead to significant modifications.Comment: 5 pages, 2 Figures, RevTe
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