Squeezed states and thermally excited states in the wigner phase-space picture of quantum mechanics

The phase-space picture of thermal excitations is presented starting from the formalism of two-mode coherent and squeezed states. It is shown that the thermal degree of freedom can be augmented into the existing formalism of coherent and squeezed states. It is shown further that the thermal excitation leads to a diametric expansion of the Wigner phase-space distribution function.