A simple nonlinear dissipative quantum evolution equation

The author has considered a nonlinear dissipative evolution equation that generalises the Schrodinger equation. In the corresponding evolution all the stationary states of the usual Schrodinger equation have a behaviour of semistable limit cycles, except the ground state which is stable. The model is applied to the spin-1/2 and to the damped harmonic oscillator. For the latter it is shown that the coherent states remain coherent and evolve as in the corresponding classical problem.