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Physical Review A

Ground state of an ultrastrongly coupled qubit-oscillator system with broken inversion symmetry

Li-Tuo Shen, Zhen‐Biao Yang, Huai‐Zhi Wu, Shi‐Biao Zheng

Published Jun 22, 2016• 10 citations
Publisher

Abstract

We study the effect of inversion symmetry breaking on properties of the ground state of a qubit-oscillator system within the ultrastrong-coupling regime. We obtain the solution of the ground state through the approximate analytical approach, which, under the near-resonance condition, agrees well with the numerical simulation. We demonstrate that, due to the inversion symmetry breaking, the ground state becomes asymmetric and the qubit-oscillator entanglement entropy strongly depends on the mean dipole moments. Furthermore, we find that the attainable maximum entanglement entropy undergoes a sharp change across a critical point and the minimum value of the Wigner function has a quadratic dependence on the mean dipole moments.

DOI
10.1103/physreva.93.063837

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