Creating Bell states and decoherence effects in a quantum-dot system - art. no. 062307

We show how to improve efficiency in preparing Bell states in a coupled two -quantum-dot system, which was introduced by Quiroga and Johnson [Phys. Rev . Lett. 83, 2270 (1999)]. A measurement of the state of a driven quantum la ser field leads to wave-function collapse. This results in the highly effic ient preparation of Bell states. The effect of decoherence on the efficienc y of generating Bell states is also discussed in this paper. The results sh ow that decoherence does not affect the relative weight of \ 00 > and \ 11 > in the output state, but does affect the efficiency of finding Bell state s.