Frontiers of Physics

Entanglement and excited-state quantum phase transition in an extended Dicke model

Gui‐Lei Zhu, Xin‐You Lü, Shang-Wu Bin, You Cai, Ying Wu

Published Sep 3, 2019• 13 citations

Abstract

We investigate the properties of entanglement and excited-state quantum phase transition (ESQPT) in a hybrid atom-optomechanical system in which an optomechanical quadratic interaction is introduced into a normal Dicke model. Interestingly, by preparing the ancillary mode in a coherent state, both the quantum entanglement and ESQPT can be realized in a relative weak-coupling condition. Moreover, the entanglement is immune to the A 2 term, and a reversed trend of the entropy is obtained when the A 2 term is included. Density of states (DoS) and Peres lattice are used to investigate ESQPTs. Compared to a normal Dicke model, the DoS enlarges exp(2 r α ) times if the ancillary mode is prepared in a coherent state. This work is an extension of the ground-state quantum phase transition, which may inspire further exploration of the quantum criticality in many-body systems.

DOI: 10.1007/s11467-019-0921-4

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