QUANTUM DISSIPATION AND COHERENCE
Abstract
We discuss dissipative systems in Quantum Field Theory by studying the canonical quantization of the damped harmonic oscillator (dho). We show that the set of states of the system splits into unitarily inequivalent representations of the canonical commutation relations. The irreversibility of time evolution is expressed as tunneling among the unitarily inequivalent representations. Canonical quantization is shown to lead to time dependent SU(1,1) coherent states. We derive the exact action for the dho from the path integral formulation of the quantum Brownian motion developed by Schwinger and by Feynman and Vernon. The doubling of the phasespace degrees of freedom for dissipative systems is related to quantum noise effects. Finally, we express the time evolution generator of the dho in terms of operators of the $q$deformation of the WeylHeisenberg algebra. The $q$parameter acts as a label for the unitarily inequivalent representations.
 Publication:

arXiv eprints
 Pub Date:
 March 1995
 arXiv:
 arXiv:hepth/9503135
 Bibcode:
 1995hep.th....3135V
 Keywords:

 High Energy Physics  Theory;
 Quantum Physics
 EPrint:
 Invited talk at the Workshop on Quantumlike models and coherent effects, Erice, Sicily, 1320 June 1994.