  In the framework of Lindblad theory for open quantum systems, we calculate
the entropy of a damped quantum harmonic oscillator which is initially in a
quasi-free state. The maximally predictable states are identified as those
states producing the minimum entropy increase after a long enough time. In
general, the states with a squeezing parameter depending on the environment's
diffusion coefficients and friction constant are singled out, but if the
friction constant is much smaller than the oscillator's frequency, coherent
states
  (or thermalized coherent states) are obtained as the preferred classical
states.
