Decoherence as a Signature of an Excited State Quantum Phase Transition in Two Level Boson Systems

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García Ramos, J. E.
Arias, J. M.
Dukelsky, J.
Pérez Fernández, P.
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American Institute of Physics (AIP)
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We analyze the decoherence induced on a single qubit by the interaction with a two-level boson system with critical internal dynamics. We explore how the decoherence process is affected by the presence of quantum phase transitions in the environment. We conclude that the dynamics of the qubit changes dramatically when the environment passes through a continuous excited state quantum phase transition. If the system-environment coupling energy equals the energy at which the environment has a critical behavior, the decoherence induced on the qubit is maximal and the fidelity tends to zero with finite size scaling obeying a power-law.
© 2009 American Institute of Physics. International Conference Nuclear Structure and Dynamics (1ª. 2009. Dubrovnik (Croacia). This work has been partially supported by the Spanish MEC (FEDER) under projects number FIS2006-12783-C03-01, FPA2007-63074 and FIS2008-04189, by Comunidad de Madrid and CSIC under project 200650M012, by Junta de Andalucia under projects FQM160, FQM318, P05-FQM437 and P07-FQM-02962 and by the Spanish Consolider-Ingenio 2010 Programme CPAN (CSD2007-00042). A.R. is supported by the Spanish program "Juan de la Cierva", and P. P-F., by a grant from the Spanish MEC.
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