DECOHERENCE AND DISSIPATION IN QUANTUM 2-STATE SYSTEMS

The Brownian dynamics of the density operator for a quantum system int eracting with a classical heat bath is described using a stochastic, n on-linear Liouville equation obtained from a variational principle. Th e rate of the noise-induced transitions is expressed as a function of the environmental spectral density, and is discussed for the case of w hite noise and blackbody radiation. The time-scales of decoherence and dissipation are investigated numerically for a system of two quantum states. These are the ground and first excited state of the center of mass vibrations for a single ion confined in a harmonic trap. (C) 1998 Elsevier Science B.V. All rights reserved.