Pérez Fernández, PedroRelaño Pérez, ArmandoArias Carrasco, José MiguelDukelsky, J.García Ramos, José Enrique2012-02-012012-02-012009-09-17Pérez Fernández, P., Relaño Pérez, A., Arias Carrasco, J.M., Dukelsky, J., García Ramos, J.E.: "Decoherence due to an excited state quantum phase transition in a two-level boson model". Physical Review A. Vol. 80, n. 3 (2009). ISSN 1050-29471050-2947http://hdl.handle.net/10272/5450The 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.engAtribución-NoComercial-SinDerivadas 3.0 Españahttp://creativecommons.org/licenses/by-nc-nd/3.0/es/BosonesQuanta, Teoría de losjournal articleopen access