Volume 87, Number 2, July 2009
Article Number 20002
Number of page(s) 6
Section General
Published online 30 July 2009
EPL, 87 (2009) 20002
DOI: 10.1209/0295-5075/87/20002

Quantum quench from a thermal initial state

S. Sotiriadis1, P. Calabrese2 and J. Cardy1, 3

1   Oxford University, Rudolf Peierls Centre for Theoretical Physics - 1 Keble Road, Oxford OX1 3NP, UK, EU
2   Dipartimento di Fisica Enrico Fermi, Università di Pisa - Largo Bruno Pontecorvo 3, 56127 Pisa, Italy, EU
3   All Souls College - High Street, Oxford OX1 4AL, UK, EU

received 18 March 2009; accepted in final form 6 July 2009; published July 2009
published online 30 July 2009

We consider a quantum quench in a system of free bosons, starting from a thermal initial state. As in the case where the system is initially in the ground state, any finite subsystem eventually reaches a stationary thermal state with a momentum-dependent effective temperature. We find that this can, in some cases, even be lower than the initial temperature. We also study lattice effects and discuss more general types of quenches.

03.75.Kk - Dynamic properties of condensates; collective and hydrodynamic excitations, superfluid flow.
05.30.-d - Quantum statistical mechanics.

© EPLA 2009