Open quantum systems with loss and gain
Abstract
We consider different properties of small open quantum systems coupled to an environment and described by a non-Hermitian Hamilton operator. Of special interest is the non-analytical behavior of the eigenvalues in the vicinity of singular points, the so-called exceptional points (EPs), at which the eigenvalues of two states coalesce and the corresponding eigenfunctions are linearly dependent from one another. The phases of the eigenfunctions are not rigid in approaching an EP and providing therewith the possibility to put information from the environment into the system. All characteristic properties of non-Hermitian quantum systems hold true not only for natural open quantum systems that suffer loss due to their embedding into the continuum of scattering wavefunctions. They appear also in systems coupled to different layers some of which provide gain to the system. Thereby gain and loss, respectively, may be fixed inside every layer, i.e. characteristic of it.
Cite
@article{arxiv.1409.2670,
title = {Open quantum systems with loss and gain},
author = {Hichem Eleuch and Ingrid Rotter},
journal= {arXiv preprint arXiv:1409.2670},
year = {2015}
}
Comments
Correction of a few misprints; addition of a few new references; paper will appear in a Special Issue of International Journal of Theoretical Physics related to several conferences on PHHQP in 2014; accepted 10 October 2014; available: DOI 10.1007/s10773-014-2375-3