Universal fluctuations and squeezing in a generalized Dicke model near the superradiant phase transition

Shapiro, D. S.; Pogosov, W. V.; Lozovik, Yu. E.

doi:10.1103/physreva.102.023703

Cited by 29 publications

(28 citation statements)

References 46 publications

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“…by heterodyne detection [62]. Moreover, our methods could in principle be applied to analyze several other systems in which superradiant phase transitions of both first and second order have been discovered [63][64][65][66][67][68][69][70][71][72]. Finally, and quite interestingly, our methods are directly applicable to open quantum systems.…”

Section: Discussionmentioning

confidence: 85%

Multipartite quantum correlations in a two-mode Dicke model

Soldati,

Mitchison,

Landi

2021

Preprint

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We analyze multipartite correlations in a generalized Dicke model involving two optical modes interacting with an ensemble of two-level atoms. In particular, we examine correlations beyond the standard bipartite entanglement and derive exact results in the thermodynamic limit. The model presents two superradiant phases involving the spontaneous breaking of either a Z 2 or U(1) symmetry. The latter is characterized by the emergence of a Goldstone excitation, found to significantly affect the correlation profiles. Focusing on the correlations between macroscopic subsystems, we analyze both the mutual information as well as the entanglement of formation for all possible bipartitions among the optical and matter degrees of freedom. It is found that while each mode entangles with the atoms, the bipartite entanglement between the modes is zero, and they share only classical correlations and quantum discord. We also study the monogamy of multipartite entanglement and show that there exists genuine tripartite entanglement, i.e. quantum correlations that the atoms share with the two modes but that are not shared with them individually, only in the vicinity of the critical lines. Our results elucidate the intricate correlation structures underlying superradiant phase transitions in multimode systems.

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Section: Discussionmentioning

confidence: 85%

Multipartite quantum correlations in a two-mode Dicke model

Soldati,

Mitchison,

Landi

2021

Preprint

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“…This applies, e.g., to single-electron transistors 48 , to helical electrons scattering 49 , 50 and to multiple Andreev reflection in superconducting junctions 51 . In our optical system, it can be associated with the emergence of positive ( ) and negative ( ) correlations between photons 52 , 53 .…”

Section: Resultsmentioning

confidence: 99%

Transport of pseudothermal photons through an anharmonic cavity

Shapiro

2021

Sci Rep

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Under nonequilibrium conditions, quantum optical systems reveal unusual properties that might be distinct from those in condensed matter. The fundamental reason is that photonic eigenstates can have arbitrary occupation numbers, whereas in electronic systems these are limited by the Pauli principle. Here, we address the steady-state transport of pseudothermal photons between two waveguides connected through a cavity with Bose–Hubbard interaction between photons. One of the waveguides is subjected to a broadband incoherent pumping. We predict a continuous transition between the regimes of Lorentzian and Gaussian chaotic light emitted by the cavity. The rich variety of nonequilibrium transport regimes is revealed by the zero-frequency noise. There are three limiting cases, in which the noise-current relation is characterized by a power-law, $$S\propto J^\gamma$$ S ∝ J γ . The Lorentzian light corresponds to Breit-Wigner-like transmission and $$\gamma =2$$ γ = 2 . The Gaussian regime corresponds to many-body transport with the shot noise ($$\gamma =1$$ γ = 1 ) at large currents; at low currents, however, we find an unconventional exponent $$\gamma =3/2$$ γ = 3 / 2 indicating a nontrivial interplay between multi-photon transitions and incoherent pumping. The nonperturbative solution for photon dephasing is obtained in the framework of the Keldysh field theory and Caldeira-Leggett effective action. These findings might be relevant for experiments on photon blockade in superconducting qubits, thermal states transfer, and photon statistics probing.

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“…The thermal SRPT in ErFeO 3 would exhibit rich physics beyond the quantum or zero-temperature SRPT that has been demonstrated in laser-driven cold atoms [14][15][16][17] . It is known that the thermal and quantum fluctuations of photons and atoms exhibit characteristic behaviours around the SRPT 74,75 . Recent studies have reported the occurrence of strong, two-mode quantum squeezing at the SRPT critical point 12,13 .…”

Section: Discussionmentioning

confidence: 99%

Magnonic superradiant phase transition

Bamba

Peraca

et al. 2022

Commun Phys

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In the superradiant phase transition (SRPT), coherent light and matter fields are expected to appear spontaneously in a coupled light–matter system in thermal equilibrium. However, such an equilibrium SRPT is forbidden in the case of charge-based light–matter coupling, known as no-go theorems. Here, we show that the low-temperature phase transition of ErFeO3 at a critical temperature of approximately 4 K is an equilibrium SRPT achieved through coupling between Fe3+ magnons and Er3+ spins. By verifying the efficacy of our spin model using realistic parameters evaluated via terahertz magnetospectroscopy and magnetization experiments, we demonstrate that the cooperative, ultrastrong magnon–spin coupling causes the phase transition. In contrast to prior studies on laser-driven non-equilibrium SRPTs in atomic systems, the magnonic SRPT in ErFeO3 occurs in thermal equilibrium in accordance with the originally envisioned SRPT, thereby yielding a unique ground state of a hybrid system in the ultrastrong coupling regime.

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Universal fluctuations and squeezing in a generalized Dicke model near the superradiant phase transition

Cited by 29 publications

References 46 publications

Multipartite quantum correlations in a two-mode Dicke model

Multipartite quantum correlations in a two-mode Dicke model

Transport of pseudothermal photons through an anharmonic cavity

Magnonic superradiant phase transition

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