Eur. Phys. J. B (2013) 86: 176
https://doi.org/10.1140/epjb/e2013-31010-0

Regular Article

Steady Schrödinger cat state of a driven Ising chain

Laboratoire de Physique Théorique de la Matière Condensée, UMR 7600, Université Pierre et Marie Curie, Jussieu, 75005 Paris, France

^a e-mail: camalet@lptmc.jussieu.fr

Received: 5 November 2012
Received in final form: 16 February 2013
Published online: 22 April 2013

Abstract

For short-range interacting systems, no Schrödinger cat state can be stable when their environment is in thermal equilibrium. We show, by studying a chain of two-level systems with nearest-neighbour Ising interactions, that this is possible when the surroundings consists of two heat reservoirs at different temperatures, or of a heat reservoir and a monochromatic field. The asymptotic state of the considered system can be a pure superposition of mesoscopically distinct states, the all-spin-up and all-spin-down states, at low temperatures. The main feature of our model leading to this result is the fact that the Hamiltonian of the chain and the dominant part of its coupling to the environment obey the same symmetry.