Exploiting randomness in quantum information processing

We consider how randomness can be made to play a useful role in quantum information processing-in particular, for decoherence control and the implementation of quantum algorithms. For a two-level system in which the decoherence channel is non-dissipative, we show that decoherence suppression is possible if memory is present in the channel. Random switching between two potentially harmful noise sources can then provide a source of stochastic control. Such random switching can also be used in an advantageous way for the implementation of quantum algorithms. (C) 2002 Elsevier Science B.V. All rights reserved.