109 research outputs found
Storage States in Ultracold Collective Atoms
We present a complete theoretical description of atomic storage states in the
multimode framework by including spatial coherence in atomic collective
operators and atomic storage states. We show that atomic storage states are
Dicke states with the maximum cooperation number. In some limits, a set of
multimode atomic storage states has been established in correspondence with
multimode Fock states of the electromagnetic field. This gives better
understanding of both the quantum and coherent information of optical field can
be preserved and recovered in ultracold medium. In this treatment, we discuss
in detail both the adiabatic and dynamic transfer of quantum information
between the field and the ultracold medium.Comment: 22 pages, no figures;to be published in Euro. Phys. J.
Quantum tunneling time of a Bose-Einstein condensate traversing through a laser-induced potential barrier
We theoretically study the effect of atomic nonlinearity on the tunneling
time in the case of an atomic Bose-Einstein condensate (BEC) traversing the
laser-induced potential barrier. The atomic nonlinearity is controlled to
appear only in the region of the barrier by employing the Feshbach resonance
technique to tune interatomic interaction in the tunneling process. Numerical
simulation shows that the atomic nonlinear effect dramatically changes the
tunneling behavior of the BEC matter wave packet, and results in the violation
of Hartman effect and the occurrence of negative tunneling time.Comment: 4 pages, 5 figure
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