Decoherence for phase-sensitive relaxation.pdf

a r X i v : q u a n t - p h / 9 7 0 7 0 5 4 v 2 2 M a r 1 9 9 9 Decoherence for phase-sensitive relaxation Dmitriy Kilin and Michael Schreiber Institut fu?r Physik, Technische Universita?t, D-09107 Chemnitz, Germany (February 1, 2008) Abstract It is shown that the vibrational wave packet relaxation of initially co- herent (displaced) states as well as the quantum superposition of coherent states in heat bathes with the different spectral densities exhibit a number of peculiarities compared with the cases of linear phase-sensitive relaxation, quadratic relaxation, and relaxational dynamics described with the use of Zurek’s environmentally-induced pointer basis. A strong dependence of the relaxation rate on the position of the spectral density maximum of the bath is found. The differences can be used for the discrimination of the mechanisms of the molecule-environment interactions. PACS number(s): 82.29.Rp, 33.80.Be, 32.80.Bx, 31.70.Hq Typeset using REVTEX 1 I. INTRODUCTION The behavior of many quantum systems strongly depends on their interaction with the environment. It is important to take this interaction into account to realistically describe systems like, e.g., vibrational levels in a big molecule, the quantized mode of an electromag- netic field, or a trapped ion. The rapid development of experimental techniques in these and other branches of physics and chemistry leads to an increased interest in theoretical de- scriptions of possible experiments by numerical calculations. Additionally our calculations, which concern such systems, allow us to regard the still existing question about the border between classical and quantum effects from a new point of view. For the systems, which are described here, the border to disappearance of quantum effects has been estimated. One of the fundamental questions of quantum physics is to understand why the general principle of superposition works very well in microscopic physics but leads to paradox situa- tions in macros