Subluminal to superluminal propagation of an optical pulse in an f-deformed Bose-Einstein condensate

Abstract

In this paper, we investigate the propagation of a weak optical probe pulse in an f-deformed Bose-Einstein condensate of a gas with the Λ-type three-level atoms in the electromagnetically induced transparency regime. We use an f-deformed generalization of an effective two-level quantum model of the three-level Λ configuration in which Gardiner's phonon operators for Bose-Einstein condensates are deformed by an operator-valued function,f (n̂), of the particle-number operator n̂. By making use of the quantum approach of the angular momentum theory, we obtain the eigenvalues and eigenfunctions of the system up to a first-order approximation. We consider the collisions between the atoms as a special kind of f-deformation. The collision rate κ is regarded as the deformation parameter and light propagation in the deformed Bose-Einstein condensate is analysed. In particular, we show that the absorptive and dispersive properties of the deformed condensate can be controlled effectively by changing the deformation parameter κ and the total number of atoms. We find that by increasing the value of κ the group velocity of the probe pulse changes, through deformed condensate, from subluminal to superluminal. © 2008 IOP Publishing Ltd.