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Main Authors: Lian, Jinling, Huang, Ran, Gao, Chao, Yu, Lixian, Liang, Qi-Feng, Liu, Wu-Ming
Format: Preprint
Published: 2024
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Online Access:https://arxiv.org/abs/2408.10121
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author Lian, Jinling
Huang, Ran
Gao, Chao
Yu, Lixian
Liang, Qi-Feng
Liu, Wu-Ming
author_facet Lian, Jinling
Huang, Ran
Gao, Chao
Yu, Lixian
Liang, Qi-Feng
Liu, Wu-Ming
contents We investigate the ground-state properties and quantum phase transitions of an ensemble consisting of $N$ four-level atoms within an optical cavity coupled to the single cavity mode and external laser fields. The system is described by an extended imbalanced Dicke model, in which the co- and counterrotating coupling terms are allowed to have different coupling strengths. Some novel polarized phases characterized by the phase differences between the cavity field or the atomic spin excitation and the Raman laser are found analytically. Meanwhile, the full phase diagram and quantum phase transitions are also revealed. Finally, the breaking or restoration of the intrinsic symmetry in this system is addressed. It is found that besides the continuous $U(1)$ and discrete $\mathbb{Z}_2$ symmetries, the system also exhibits two reflection symmetries $σ_v$s, a central symmetry $C_2$ in the abstract position-momentum representation, and a discrete reflection parity-time ($\mathcal{PT}$) symmetry, a parameter exchange symmetry $\mathcal{T}_\mathrm{ex}$ in the parameters space. These additional symmetries are governed by two Coxeter groups.
format Preprint
id arxiv_https___arxiv_org_abs_2408_10121
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Spontaneous polarized phase transitions and symmetry breaking of an ultracold atomic ensemble in a Raman-assisted cavity
Lian, Jinling
Huang, Ran
Gao, Chao
Yu, Lixian
Liang, Qi-Feng
Liu, Wu-Ming
Quantum Physics
We investigate the ground-state properties and quantum phase transitions of an ensemble consisting of $N$ four-level atoms within an optical cavity coupled to the single cavity mode and external laser fields. The system is described by an extended imbalanced Dicke model, in which the co- and counterrotating coupling terms are allowed to have different coupling strengths. Some novel polarized phases characterized by the phase differences between the cavity field or the atomic spin excitation and the Raman laser are found analytically. Meanwhile, the full phase diagram and quantum phase transitions are also revealed. Finally, the breaking or restoration of the intrinsic symmetry in this system is addressed. It is found that besides the continuous $U(1)$ and discrete $\mathbb{Z}_2$ symmetries, the system also exhibits two reflection symmetries $σ_v$s, a central symmetry $C_2$ in the abstract position-momentum representation, and a discrete reflection parity-time ($\mathcal{PT}$) symmetry, a parameter exchange symmetry $\mathcal{T}_\mathrm{ex}$ in the parameters space. These additional symmetries are governed by two Coxeter groups.
title Spontaneous polarized phase transitions and symmetry breaking of an ultracold atomic ensemble in a Raman-assisted cavity
topic Quantum Physics
url https://arxiv.org/abs/2408.10121