Photon Creation viewed from Wigner's Phase Space Current Perspective: The Simplest Possible Derivation of a Lindblad Superoperator Form

For the study of quantum dynamics the use of Wigner's phase space representation can be rewarding. It describes the state by Wigner's real-valued distribution W and its dynamics by a vector field in phase space, the Wigner current J . Basically, only the Wigner representation can be used for this type of visual study of quantum dynamics so conveniently and directly. What does it teach us about the most fundamental ingredient of quantum dynamics, the quantum jump between energy levels? Quite a lot, as it turns out.