Phys. Rev. A 76, 012104 (2007) [9 pages]Quantum critical dynamics of a qubit coupled to an isotropic Lipkin-Meshkov-Glick bathReceived 3 March 2007; published 9 July 2007 We explore a dynamic signature of quantum phase transition (QPT) in an isotropic Lipkin-Meshkov-Glick (LMG) model by studying the time evolution of a central qubit coupled to it. We evaluate exactly the time-dependent purity, which can be used to measure quantum coherence, of the central qubit. It is found that distinctly different behaviors of the purity as a function of the parameter reveal clearly the QPT point in the system. It is also clarified that the present model is equivalent to an anti–Jaynes-Cummings model under certain conditions. © 2007 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevA.76.012104
DOI:
10.1103/PhysRevA.76.012104
PACS:
03.65.Yz, 05.70.−a, 05.90.+m
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