### Abstract

We investigate the finite-size Dicke model with photon leakage. It is shown that the symmetry breaking states, which are characterized by non-vanishing 〈aˆ〉≠0 and correspond to the ground states in the superradiant phase in the thermodynamic limit, are stable, while the eigenstates of the isolated finite-size Dicke Hamiltonian conserve parity symmetry. We introduce and analyze an effective master equation that describes the dynamics of a pair of the symmetry breaking states that are the degenerate lowest energy eigenstates in the superradiant region with photon leakage. It becomes clear that photon leakage is essential to stabilize the symmetry breaking states and to realize the superradiant phase without the thermodynamic limit. Our theoretical analysis provides an alternative interpretation using the finite-size model to explain results from cold atomic experiments showing superradiance with the symmetry breaking in an optical cavity.

Original language | English |
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Journal | Physics Letters, Section A: General, Atomic and Solid State Physics |

DOIs | |

Publication status | Accepted/In press - 2018 Jan 1 |

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### Keywords

- Decoherence
- Dicke model
- Open quantum system
- Quantum phase transition
- Superradiance

### ASJC Scopus subject areas

- Physics and Astronomy(all)

### Cite this

**Stability of symmetry breaking states in finite-size Dicke model with photon leakage.** / Imai, Ryosuke; Yamanaka, Yoshiya.

Research output: Contribution to journal › Article

}

TY - JOUR

T1 - Stability of symmetry breaking states in finite-size Dicke model with photon leakage

AU - Imai, Ryosuke

AU - Yamanaka, Yoshiya

PY - 2018/1/1

Y1 - 2018/1/1

N2 - We investigate the finite-size Dicke model with photon leakage. It is shown that the symmetry breaking states, which are characterized by non-vanishing 〈aˆ〉≠0 and correspond to the ground states in the superradiant phase in the thermodynamic limit, are stable, while the eigenstates of the isolated finite-size Dicke Hamiltonian conserve parity symmetry. We introduce and analyze an effective master equation that describes the dynamics of a pair of the symmetry breaking states that are the degenerate lowest energy eigenstates in the superradiant region with photon leakage. It becomes clear that photon leakage is essential to stabilize the symmetry breaking states and to realize the superradiant phase without the thermodynamic limit. Our theoretical analysis provides an alternative interpretation using the finite-size model to explain results from cold atomic experiments showing superradiance with the symmetry breaking in an optical cavity.

AB - We investigate the finite-size Dicke model with photon leakage. It is shown that the symmetry breaking states, which are characterized by non-vanishing 〈aˆ〉≠0 and correspond to the ground states in the superradiant phase in the thermodynamic limit, are stable, while the eigenstates of the isolated finite-size Dicke Hamiltonian conserve parity symmetry. We introduce and analyze an effective master equation that describes the dynamics of a pair of the symmetry breaking states that are the degenerate lowest energy eigenstates in the superradiant region with photon leakage. It becomes clear that photon leakage is essential to stabilize the symmetry breaking states and to realize the superradiant phase without the thermodynamic limit. Our theoretical analysis provides an alternative interpretation using the finite-size model to explain results from cold atomic experiments showing superradiance with the symmetry breaking in an optical cavity.

KW - Decoherence

KW - Dicke model

KW - Open quantum system

KW - Quantum phase transition

KW - Superradiance

UR - http://www.scopus.com/inward/record.url?scp=85053011714&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85053011714&partnerID=8YFLogxK

U2 - 10.1016/j.physleta.2018.09.002

DO - 10.1016/j.physleta.2018.09.002

M3 - Article

AN - SCOPUS:85053011714

JO - Physics Letters, Section A: General, Atomic and Solid State Physics

JF - Physics Letters, Section A: General, Atomic and Solid State Physics

SN - 0375-9601

ER -