Eur. Phys. J. D (2017) 71: 144
https://doi.org/10.1140/epjd/e2017-80011-4

Regular Article

Generation of quantum discord in two-mode Gaussian systems in a thermal reservoir

¹ Department of Theoretical Physics, National Institute of Physics and Nuclear Engineering, Bucharest-Magurele, P.O. Box MG-6, Romania
² Faculty of Physics, University of Bucharest, Bucharest-Magurele, P.O. Box MG-11, Romania

^a e-mail: isar@theory.nipne.ro

Received: 4 January 2017
Received in final form: 20 April 2017
Published online: 9 June 2017

Abstract

In the framework of the theory of open quantum systems based on completely positive dynamical semigroups, we study the Gaussian quantum discord for a subsystem composed of two coupled bosonic modes immersed in a thermal environment. For Gaussian input states, the time evolution of discord is given in terms of the covariance matrix. For initial uni-modal squeezed states the generation of Gaussian discord takes place, for all non-zero values of the strength of interaction between the bosonic modes. After reaching some maximum value in the case of initial uni-modal squeezed states, and also for initial squeezed vacuum states with non-zero Gaussian discord, this measure of quantum correlations non-monotonically decreases in time and tends asymptotically for large times to some definite non-zero value. The asymptotic discord depends on the strength of interaction between the bosonic modes, temperature and dissipation coefficient.