Multipartite quantum correlations in a two-mode Dicke model

Soldati, Rodolfo; Mitchison, Mark T.; Landi, Gabriel T.

doi:10.1103/physreva.104.052423

Cited by 18 publications

(7 citation statements)

References 83 publications

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“…multi-critical behaviour in variants of the Rabi and Dicke models [49][50][51][52][53][54], in which phase transitions have been experimentally observed [55][56][57]. The fluctuations of measurement currents in these systems will thus contain a wealth of information about their nonequilibrium phase diagrams.…”

Section: Discussionmentioning

confidence: 99%

Diverging current fluctuations in critical Kerr resonators

Kewming,

Mitchison,

Landi

2022

Preprint

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The parametrically pumped Kerr model describes a driven-dissipative nonlinear cavity, whose nonequilibrium phase diagram features both continuous and discontinuous quantum phase transitions. We consider the consequences of these critical phenomena for the fluctuations of the photocurrent obtained via continuous weak measurements on the cavity. Considering both direct photodetection and homodyne detection schemes, we find that the current fluctuations diverge exponentially at the discontinuous phase transition. However, we find strikingly different current fluctuations for these two detection schemes near the continuous transition, a behaviour which is explained by the complementary information revealed by measurements in different bases. To obtain these results, we develop formulas to efficiently compute the diffusion coefficient-which characterises the long-time current fluctuations-directly from the quantum master equation, thus connecting the formalisms of full counting statistics and stochastic quantum trajectories. Our findings highlight the rich features of current fluctuations near nonequilibrium phase transitions in quantum-optical systems.

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Section: Discussionmentioning

confidence: 99%

Diverging current fluctuations in critical Kerr resonators

Kewming,

Mitchison,

Landi

2022

Preprint

Self Cite

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“…However, one needs to go beyond the mean-field approach to study the correlations between different large spins, as well as the quantum fluctuations. To separate the mean-field contribution and the higher-order terms, we first perform a unitary transformation [12,34,38], which leads to The unitary transformation Û brings the rotated z axis along the direction of the large spin obtained from the mean-field approach [34].…”

Section: Beyond Mean-field Approachmentioning

confidence: 99%

Quantum phase transitions in the triangular coupled-top model

Duan¹,

Wang²,

Chen³

2022

Preprint

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We study the coupled-top model with three large spins located on a triangle. Depending on the coupling strength, there exist three phases: disordered paramagnetic phase, ferromagnetic phase, and frustrated antiferromagnetic phase, which can be distinguished by the mean-field approach. The paramagnetic-ferromagnetic phase transition is accompanied by the breaking of the global Z2 symmetry, whereas the paramagnetic-antiferromagnetic phase transition is accompanied by the breaking of both the global Z2 symmetry and the translational symmetry. Exact analytical results of higherorder quantum effects beyond the mean-field contribution, such as the excitation energy, quantum fluctuation and von Neumann entropy, can be achieved by the Holstein-Primakoff transformation and symplectic transformation in the thermodynamic limit. Near the quantum critical point, the energy gap closes, along with the divergence of the quantum fluctuation in certain quadrature and von Neumann entropy. Particular attention should be paid to the antiferromagnetic phase, where the geometric frustration takes effect. The critical behaviors in the antiferromagnetic phase are quite different from those in the paramagnetic and ferromagnetic phases, which highlights the importance of the geometric frustration. The triangular coupled-top model provides a simple and feasible platform to study the quantum phase transition and the novel critical behaviors induced by the geometric frustration.

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“…We have shown in this work that relevant and non-trivial properties of classical and quantum correlations present themselves in the equilibrium quantum phases of a Dicke model, extended to have two modes coupling with their own strengths to different components of the collective spin degrees of freedom [39].…”

Section: Summary Of Chaptermentioning

confidence: 92%

“…We can compute numerically E 2 (A i ;A j :A k ) with two choices of focus mode, X and J (the measure is symmetric in the other arguments) [39]. We can point out that this quantity becomes permutation invariant in all arguments for fully inseparable states, which is never our case, since E 2 (X :Y ) = 0 in all parameter regions.…”

Section: 97)mentioning

confidence: 98%

“…Next, in chapter 3, from [39], we end the thesis by moving our focus to the more intricate platform of interacting spin-boson systems, where collective behavior, phases of matter and many-body physics are key underlying concepts. The well-established Dicke model, often useful in quantum optics and atomic physics [40][41][42], will serve us in a study of equilibrium properties of a system amenable to the autonomous absorption refrigerator design.…”

Section: Background and Motivationmentioning

confidence: 99%

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Refrigeração quântica: termodinâmica e informação

Soldati

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The theory of cooling is an important corner of thermodynamics, underlying many modern technological applications. As the field of quantum thermodynamics advances, refrigeration techniques must keep pace to fuel the innovations of quantum technologies. We study quantum cooling from its foundations to laboratory implementations within the specific paradigm of heat bath algorithmic cooling. Our study includes a detail modeling of experimental imperfections and establishes the fundamental cooling limits of the model, consolidating the algorithm as a viable quantum refrigeration method. Next, by developing the notion of virtual qubits, we demonstrate a cooling-boost protocol fueled by quantum coherences which is robust to experimental implementations. Aiming at aiding in the progress of refrigeration technologies, we conclude by studying the zero temperature equilibrium properties of a many-body system that can accommodate an autonomous quantum absorption refrigerator, and calculate its entanglement and critical properties, two features that, like quantum coherences, promise to improve the performance of quantum coolers.

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Multipartite quantum correlations in a two-mode Dicke model

Cited by 18 publications

References 83 publications

Diverging current fluctuations in critical Kerr resonators

Diverging current fluctuations in critical Kerr resonators

Quantum phase transitions in the triangular coupled-top model

Refrigeração quântica: termodinâmica e informação

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