Decoherence due to an excited-state quantum phase transition in a two-level boson model



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Relaño Pérez, Armando and Pérez Fernández, P. and Arias, J. M. and Dukelsky, J. and García Ramos, J. E. (2009) Decoherence due to an excited-state quantum phase transition in a two-level boson model. Physical Review A, 80 (3). ISSN 1050-2947

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The decoherence induced on a single qubit by its interaction with the environment is studied. The environment is modeled as a scalar two-level boson system that can go through either first-order or continuous-excited-state quantum phase transitions, depending on the values of the control parameters. A mean-field method based on the Tamm-Damkoff approximation is worked out in order to understand the observed behavior of the decoherence. Only the continuous-excited-state phase transition produces a noticeable effect in the decoherence of the qubit. This is maximal when the system-environment coupling brings the environment to the critical point for the continuous phase transition. In this situation, the decoherence factor (or the fidelity) goes to zero with a finite-size scaling power law.

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©2009 The American Physical Society. This work has been partially supported by the Spanish Ministerio de Educacion y Ciencia and by the European regional development fund (FEDER) under Projects No. FIS2008-04189, No. FIS2006-12783-C03-01, No. FPA2006-13807-C02-02, and No. FPA2007-63074, by CPAN-Ingenio, by Comunidad de Madrid under Project No. 200650M012, CSIC, and by Junta de Analucia a under Projects No. FQM160, No. FQM318, No. P05-FQM437, and No. P07-FQM-02962. A. R. is supported by the Spanish program "Juan de la Cierva" and P. P- F. is supported by a FPU grant of the Spanish Ministerio de Educacion y Ciencia.

Uncontrolled Keywords:Lipkin Model, Systems
Subjects:Sciences > Physics > Thermodynamics
ID Code:27582
Deposited On:17 Dec 2014 10:15
Last Modified:17 Dec 2014 10:15

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