Decoherence induced by a dynamic spin environment: The universal regime

Cecilia Cormick and Juan Pablo Paz
Phys. Rev. A 77, 022317 – Published 14 February 2008

Abstract

This paper analyzes the decoherence induced on a single qubit by the interaction with a spin chain with nontrivial internal dynamics (XY-type interactions). The aim of the paper is to study the existence and properties of the so-called universal regime, in which the decoherence time scale becomes independent of the strength of the coupling with the environment. It is shown that, although such a regime does exist, as previously established by Cucchietti et al. [Phys. Rev. A 75, 032337 (2007)], it is not a clear signature of a quantum phase transition in the environment. In fact, this kind of universality also exists in the absence of quantum phase transitions. A universal regime can be related to the existence of an energy scale separation between the Hamiltonian of the environment and the one characterizing the system-environment interaction. The results presented also indicate that in the strong-coupling regime the quantum phase transition does not produce an enhancement of decoherence (as opposed to what happens in the weak-coupling regime).

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  • Received 17 September 2007

DOI:https://doi.org/10.1103/PhysRevA.77.022317

©2008 American Physical Society

Authors & Affiliations

Cecilia Cormick and Juan Pablo Paz

  • Departamento de Física, FCEyN, UBA, Ciudad Universitaria Pabellón 1, 1428 Buenos Aires, Argentina

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Vol. 77, Iss. 2 — February 2008

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