Quantum Langevin systems

Kae Nemoto

Crispin W. Gardiner, P. Zoller

Hiroshi Ueyama

An application of the method of quantum Langevin equation to a many-body system far from equilibrium is considered. A coupled set of Langevin equations is derived exactly. By approximate reductions of variables, the generalized Langevin equation of the center of mass of electrons in solid is derived, that has previously been derived on heuristic grounds.

I. R. Senitzky

It is shown that the Langevin forces needed to convert expectation-value equations into operator equations for a two-level system cannot be Gaussian, and arguments are presented for extending this result to other nonlinear systems. In order to satisfy quantum-mechanical requirements, a generalization to higher-order moments of a procedure used for specifying second-order moments of the Langevin forces is proposed.

Crispin W. Gardiner

Lorena Romero-Salazar, R. M. Velasco