Quantum quench influenced by an excited-state phase transition

©2011 American Physical Society. P.C. acknowledges useful discussions with M. Kastner and J. Hirsch. This work has been partially supported by the Czech Science Foundation (Grant No. 202/09/0084), by the Czech Ministry of Education (Grant No. MSM 0021620859), by the Spanish Ministerio de Educación y Ciencia and the European regional development fund FEDER (Grants No. FIS2009-07277, No. FIS2008-04189, No. FIS2006-12783-C03-01, No. FPA2006 13807-C02-02, No. FPA2007-63074, and No. FIS2009-11621-C02-01), by CPAN Ingenio (Grant No. CSPD-2007-00042 Ingenio), by Junta de Andalucía (Grants No. FQM160, No. FQM318, No. P05-FQM437, and No. P07-FQM-02962), and by the Universidad Complutense de Madrid (Grant No. UCM-910059). P.P-F. is supported by a FPU grant of the Spanish Ministerio de Educación y Ciencia. A.R. is supported by the Spanish program CPAN Consolider-ingenio.
We analyze excited-state quantum phase transitions (ESQPTs) in three schematic (integrable and nonintegrable) models describing a single-mode bosonic field coupled to a collection of atoms. It is shown that the presence of the ESQPT in these models affects the quantum relaxation processes following an abrupt quench in the control parameter. Clear-cut evidence of the ESQPT effects is presented in integrable models, while in a nonintegrable model the evidence is blurred due to chaotic behavior of the system in the region around the critical energy.
Czech Science Foundation
Czech Ministry of Education
Spanish Ministerio de Educación y Ciencia
FEDER
CPAN-Ingenio
Junta de Andalucía
Universidad Complutense de Madrid
Spanish program CPAN Consolider-ingenio
Depto. de Estructura de la Materia, Física Térmica y Electrónica
Fac. de Ciencias Físicas
TRUE
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