Environmental decoherence of many-body quantum systems: Semiclassical theory and simulation

In this paper, we describe an application of the trajectory-based semiclassical Lionville method for modeling coherent molecular dynamics on multiple electronic surfaces to the treatment of the evolution and decay of quantum electronic coherence in many-body systems. We consider a simple model describing coherent preparation and subsequent decoherence of a superposition of two excited electronic states of an atomic impurity in a series of rare gas solvent environments, ranging from small clusters to a cryogenic solid. The dependence of the coherent electronic dynamics on the size and temperature of the bath and on the atom-solvent interactions are investigated, and the results compared with a simple semiclassical many-body theory of ultrafast dephasing. Excellent agreement between simulation and theory is obtained, allowing accurate "back of the envelope" prediction of decoherence timescales from knowledge of the pairwise potentials, temperature of the bath, and number of solvent atoms in the local environment of the impurity. (c) 2005 Elsevier B.V. All rights reserved.