Non-rotating-wave master equation

Abstract
There has been much recent discussion of problems or unphysical results occurring from the study of the non-rotating-wave (NRW) master equations. Much of this discussion has centered on the quantum Brownian motion master equation, one particular NRW master equation. These anomalous results can occur because the (NRW) master equation is not of the ‘‘Lindblad form.’’ In this paper we discuss the limitations of the NRW master equation. Two specific examples are considered, the first being a closely spaced two-level system, while the second is the classical damped free particle. © 1996 The American Physical Society.