Quantum phase transition in the Dicke model with critical and noncritical entanglement

Bakemeier, L.; Alvermann, Andreas; Fehske, Holger

doi:10.1103/physreva.85.043821

Cited by 103 publications

(113 citation statements)

References 24 publications

(46 reference statements)

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“…We may flip the coin and consider the 'classical limit' of the harmonic oscillator instead which would be represented by ω/Ω → 0 [48]. In a set of independent papers it was realized that in such a limit critical-like behaviour and a symmetry breaking are also possible in the Rabi model [10,11,12]. for the 50 lowest energies, and C = 2500 and non-scaled frequencies ω = Ω = 1.…”

Section: The Quantum Rabi Modelmentioning

confidence: 99%

“…Following Refs. [10,11,12,13] we also analyzed the so called classical limit of the quantum Rabi and the JC models. In this limit the two models become critical, and there are many similarities with the critical behaviour of the Dicke and TC models.…”

Section: Modelmentioning

confidence: 99%

“…Here, the thermodynamic limit is identified as letting the particle number go to infinity which can be seen as the classical limit for the atomic (spin) part. Recently it was discovered that a PT also appears for only a single atom (spin-1/2) provided that the classical limit of the oscillator is taken instead [10,11,12,13].…”

Section: Introductionmentioning

confidence: 99%

“…The companion models derived by applying the rotating wave approximation (RWA) [4] to the Rabi and Dicke models, the Jaynes-Cummings [5] and Tavis-Cummings [6] models, also possess a ground state different from the vacuum in the deep strong coupling regime. Taking the proper thermodynamic limits, all four models become critical [7,8,9,10,11,12,13], i.e. the crossover turns into a true phase transition (PT) for a certain critical coupling g c .…”

Section: Introductionmentioning

confidence: 99%

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Some remarks on ‘superradiant’ phase transitions in light-matter systems

Larson

Irish

2017

J. Phys. A: Math. Theor.

107

116

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Abstract.In this paper we analyze properties of the phase transition that appears in a set of quantum optical models; Dicke, Tavis-Cummings, quantum Rabi, and finally the Jaynes-Cummings model. As the light-matter coupling is increased into the deep strong coupling regime, the ground state turns from vacuum to become a superradiant state characterized by both atomic and photonic excitations. It is pointed out that all four transitions are of the mean-field type, that quantum fluctuations are negligible, and hence these fluctuations cannot be responsible for the corresponding vacuum instability. In this respect, these are not quantum phase transitions. In the case of the Tavis-Cummings and Jaynes-Cummings models, the continuous symmetry of these models implies that quantum fluctuations are not only negligible, but strictly zero. However, all models possess a non-analyticity in the ground state in agreement with a continuous quantum phase transition. As such, it is a matter of taste whether the transitions should be termed quantum or not. In addition, we also consider the modifications of the transitions when photon losses are present. For the Dicke and Rabi models these non-equilibrium steady states remain critical, while the criticality for the open Tavis-Cummings and Jaynes-Cummings models is completely lost, i.e. in realistic settings one cannot expect a true critical behaviour for the two last models.

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Section: The Quantum Rabi Modelmentioning

confidence: 99%

Section: Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Some remarks on ‘superradiant’ phase transitions in light-matter systems

Larson

Irish

2017

J. Phys. A: Math. Theor.

107

116

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“…All these factors might contribute to the fact that the physics of the quantum Rabi model still has not been fully explored. Thus, one should face the challenge of using an intuitive way to understand the Rabi model in a general case, in which extensive physics phenomena might be involved [49][50][51][52][53][54]. In our previous work [55], we found that the deformed polaron picture is a good starting point to study the Rabi model in the whole parameter regime, and furthermore, a ground state phase diagram of the Rabi model has been extracted and some underlying physics unveiled.…”

Section: Introductionmentioning

confidence: 99%

The asymmetric quantum Rabi model in the polaron picture

Liu

Ying

et al. 2017

J. Phys. A: Math. Theor.

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The concept of the polaron in condensed matter physics has been extended to the Rabi model, where polarons resulting from the coupling between a two-level system and single-mode photons represent two oppositely displaced oscillators. Interestingly, tunneling between these two displaced oscillators can induce an anti-polaron, which has not been systematically explored in the literature, especially in the presence of an asymmetric term. In this paper, we present a systematic analysis of the competition between the polaron and anti-polaron under the interplay of the coupling strength and the asymmetric term. While intuitively the anti-polaron should be secondary owing to its higher potential energy, we find that, under certain conditions, the minor anti-polaron may gain a reversal in the weight over the major polaron. If the asymmetric amplitude ǫ is smaller than the harmonic frequency ω, such an overweighted anti-polaron can occur beyond a critical value of the coupling strength g; if ǫ is larger, the anti-polaron can even be always overweighted at any g. We propose that the explicit occurrence of the overweighted anti-polaron can be monitored by a displacement transition from negative to positive values. This displacement is an experimentally accessible observable, which can be measured by quantum optical methods, such as balanced Homodyne detection.

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Out‐of‐Time‐Order Correlators and Quantum Phase Transitions in the Rabi and Dicke Models

et al. 2020

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The out-of-time-order correlators (OTOCs) is used to study the quantum phase transitions (QPTs) between the normal phase and the superradiant phase in the Rabi and few-body Dicke models with large frequency ratio of the atomic level splitting to the single-mode electromagnetic radiation field frequency. The focus is on the OTOC thermally averaged with infinite temperature, which is an experimentally feasible quantity. It is shown that the critical points can be identified by long-time averaging of the OTOC via observing its local minimum behavior. More importantly, the scaling laws of the OTOC for QPTs are revealed by studying the experimentally accessible conditions with finite frequency ratio and finite number of atoms in the studied models. The critical exponents extracted from the scaling laws of OTOC indicate that the QPTs in the Rabi and Dicke models belong to the same universality class.

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Quantum phase transition in the Dicke model with critical and noncritical entanglement

Cited by 103 publications

References 24 publications

Some remarks on ‘superradiant’ phase transitions in light-matter systems

Some remarks on ‘superradiant’ phase transitions in light-matter systems

The asymmetric quantum Rabi model in the polaron picture

Out‐of‐Time‐Order Correlators and Quantum Phase Transitions in the Rabi and Dicke Models

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