Quantum entanglement and light propagation through Bose-Einstein condensate (BEC)

We investigate the optical response of coherent media, a Bose-Einstein condensate (BEC), to intense laser pump stimulations and weak probe pulse propagation. First, we adopt the coherence in sequential superradiance (SR) as a tool for continuous-variable (CV) quantum entanglement of two counter-propagating pulses from the two end-fire modes. In the first-sequence the end-fire and side mode are CV entangled. In the second sequence of SR, this entanglement is swapped in between the two opposite end-fire modes. Second, we investigate the photonic bands of an atomic BEC with a triangular vortex lattice. Index contrast between the vortex cores and the bulk of the condensate is achieved through the enhancement of the index via atomic coherence. Frequency dependent dielectric function is used in the calculations of the bands. We adopt a Poynting vector method to distinguish the photonic band gaps from absorption/gain regimes.