Eur. Phys. J. B (2015) 88: 89
https://doi.org/10.1140/epjb/e2015-60052-3

Regular Article

Description of non-Markovian effect in open quantum system with the discretized environment method

¹ Institut de Physique Nucléaire, IN2P3-CNRS, Université Paris-Sud, 91406 Orsay Cedex, France
² Yerevan State University, M. Manougian 1, 0025 Yerevan, Armenia
³ Joint Institute for Nuclear Research, 141980 Dubna, Russia

Received: 16 January 2015
Received in final form: 15 February 2015
Published online: 6 April 2015

Abstract

An approach, called discretized environment method, is used to treat exactly non-Markovian effects in open quantum systems. In this approach, a complex environment described by a spectral function is mapped into a finite set of discretized states with an appropriate coupling to the system of interest. The finite set of system plus environment degrees of freedom are then explicitly followed in time leading to a quasi-exact description. The present approach is anticipated to be particularly accurate in the low temperature and strongly non-Markovian regime. The discretized environment method is validated on a two-level system (qubit) coupled to a bosonic or fermionic heat-bath. A perfect agreement with the quantum Langevin approach is found. Further illustrations are made on a three-level system (qutrit) coupled to a bosonic heat-bath. Emerging processes due to strong memory effects are discussed.