Ultraslow Propagation of Entangled State via Four-Wave Mixing in a Coupled Double Quantum Well

An analytical method based on four-wave mixing (FWM) is here developed to study the generation of entangled state in an asymmetric semiconductor double quantum well structure. It is found that the maximally entangled state of two beams (the probe and four-wave mixing beams) can be achieved in an appropriate condition. Moreover, we also show that the two entangled beams propagate with ultraslow group velocity in the semiconductor medium. This investigation can be used for achieving the entangled beams in the semiconductor solid-state medium, which is much more practical than that in an atomic medium because of its flexible design and the wide adjustable parameters.