Non-Markoffian effects in the laser

Abstract

The atomic coordinates are eliminated exactly from the laser master equation with the help of a projector technique. The resulting integrodifferential equation for the field statistical operator with the kernel given correctly up to fourth order in the coupling constant is shown to be equivalent to a fourth order differential equation with respect to time. All theories footing on an “adiabatic” elimination procedure, especially the wellknown Fokker Planck equation treatment and a recently published theory containing a second order time derivative are shown to be successive approximations to our treatment. Non-Markoffian effects are discussed.