Exact master equation for an open Jaynes–Cummings system

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.