On exact master equation for an open system

Wei-Min Zhang

P. Schwendimann

Pei-Yun Yang, Wei-Min Zhang

We show that the exact master equation incorporating initial correlations for open quantum systems, within the Nakajima-Zwanzig operator-projection method, is a homegenous master equation for the reduced density matrix. We also derive explicitly the exact master equation for a large class of bosonic and fermionic open quantum systems incorporating initial correlations, the resulting master equation is homogenous. We find that the effects of the initial correlations can be fully embedded into the fluctuation dynamics through the exact homogenous master equation. Also a generalized nonequilibrium fluctuation-dissipation theorem incorporating the initial correlations is obtained.

An Min Wang

We investigate the exact solution, perturbation theory and master equation of open system dynamics based on our serial studies on quantum mechanics in general quantum systems [An Min Wang, quant-ph/0611216 and quant-ph/0611217]. In a system-environment separated representation, a general and explicit solution of open system dynamics is obtained, and it is an exact solution since it includes all order approximations of perturbation. In terms of the cut-off approximation of perturbation and our improved scheme of perturbation theory, the improved form of the perturbed solution of open systems absorbing the partial contributions from the high order even all order approximations is deduced. Moreover, only under the factorizing initial condition, the exact master equation including all order approximations is proposed. Correspondingly, the perturbed master equation and its improved form different from the existed master equation are given. In special, the Redfield master equation is derived out without using Born-Markov approximation. The solution of open system dynamics in the Milburn model is also gained. As examples, Zurek model of two-state open system and its extension with two transverse fields are studied.

L. A. Lugiato, M. Milani

Akane Watanabe, Hiromichi Nakazato

A master equation for the Jaynes-Cummings (JC) system interacting with a bosonic reservoir through a conserved quantity is derived analytically without any approximation.The derivation is valid for any initial JC state that has no correlation with the initial reservoir at any temperature and yields a Gorini-Kossakowski-Lindblad-Sudarshan-type master equation with time-dependent coefficients.Several physical quantities of the open JC system are examined and the validity or limit of some of the standard approximations used to derive the master equation is discussed on the basis of the exact results obtained here.