DESTRUCTION OF LOCALIZATION DUE TO COUPLING TO A BATH IN THE KICKED-ROTATOR PROBLEM

The quantum kicked rotator is linearly coupled to a heat bath via its momentum coordinate. A momentum-space formulation of the Feynman-Vernon formalism is introduced to find the reduced propagator. The Wigner picture of the dynamics is adopted. It is found that it is good approximation to ignore the "friction" effect and to replace the bath by a correlated noise source. For certain values of the friction coefficient, this replacement is exact. Destruction of coherence at zero temperature is qualitatively different for an undriven rotator.