Erasing information and purity of a quantum dot via its spontaneous decay

An analytical solution to the master equation of a system describing a single quantum dot confined in a single-mode microcavity, coupled to its environment, is found. The information loss of the phase space, the purity and the relaxation process are investigated by using the Husimi distribution and its applications. It is found that the spontaneous decay leads to the loss of information of the phase space and the purity. Suggested indicator for the relaxation process is offered by using the Wehrl entropy.