Abstract
In this work, the non-Markovian decoherence is considered in two ways. Firstly, an effective Hamiltonian approach is demonstrated to investigate the decoherence of a quantum system in a non-Markovian environment, in which complete positivity of the reduced dynamics is achieved. This method uses the notion of an effective environment, that is a subsystem of the environment that causes the decoherence. Secondly, the evolution of the system and environment is decomposed, thus partially illuminating how they would interact given that memory effects are allowed. It should be noted that beam splitters and rotators are sufficient to explain this decomposition.
Acknowledgments
This work was supported by the UK Engineering and Physical Sciences Research Council, the Korean Ministry of Science and Technology through the Creative Research Initiative Program under contract. 00-C-CT-01-C-35 and support by Hanyang University (HY-2003T). H McA acknowledges the Department of Employment and Learning for financial support.