Eur. Phys. J. B (2013) 86: 96
https://doi.org/10.1140/epjb/e2013-30776-1

Regular Article

Model study of dissipation in quantum phase transitions

¹ Indian Institute of Science Education and Research-Kolkata, Mohanpur, 741252 Nadia, India
² Visva-Bharati, 731235 Santiniketan, India

^a e-mail: subhasis@iiserkol.ac.in

Received: 24 August 2012
Received in final form: 30 November 2012
Published online: 13 March 2013

Abstract

We consider a prototypical system of an infinite range transverse field Ising model coupled to a bosonic bath. By integrating out the bosonic degrees, an effective anisotropic Heisenberg model is obtained for the spin system. The phase diagram of the latter is calculated as a function of coupling to the heat bath and the transverse magnetic field. Collective excitations at low temperatures are assessed within a spin-wave like analysis that exhibits a vanishing energy gap at the quantum critical point. We also discuss the possible realization and application of the model in different physical systems.