Enhanced Fermion Pairing and Superfluidity by an Imaginary Magnetic Field

Zhou, Lihong; Cui, Xiaoling

doi:10.1016/j.isci.2019.03.031

Cited by 28 publications

(16 citation statements)

References 39 publications

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“…Investigating how the interplay between two mechanisms -SOC and non-Hermiticity -may bring about new quantum phenomena, such as non-Hermitian topological phases in Bloch bands [6], will be interesting. In contrast to classical systems where only single (bosonic) particle dynamics are considered, our system sets the stage for investigating many-body interacting fermions with dissipation [46,47]. Furthermore, the possibility of exploring nonequilibrium dynamics, quantum thermodynamics [48] and information criticality [49] across the PT symmetry-breaking transition by engineering the non-Hermitian Hamiltonian in a dynamic manner is conceivable.…”

mentioning

confidence: 99%

Chiral control of quantum states in non-Hermitian spin-orbit-coupled fermions

Ren¹,

Liu²,

Zhao³

et al. 2021

Preprint

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While spin-orbit coupling (SOC), an essential mechanism underlying quantum phenomena from the spin Hall effect to topological insulators [1, 2], has been widely studied in well-isolated Hermitian systems, much less is known when the dissipation plays a major role in spin-orbit-coupled quantum systems [3]. Here, we realize dissipative spin-orbit-coupled bands filled with ultracold fermions, and observe a parity-time (PT ) symmetrybreaking transition as a result of the competition between SOC and dissipation. Tunable dissipation, introduced by state-selective atom loss, enables the energy gap, opened by SOC, to be engineered and closed at the critical dissipation value, the so-called exceptional point (EP) [4]. The realized EP of the non-Hermitian band structure exhibits chiral response when the quantum state changes near the EP. This topological feature enables us to tune SOC and dissipation dynamically in the parameter space, and observe the state evolution is direction-dependent near the EP, revealing topologically robust spin transfer between different quantum states when the quantum state encircles the EP. This topological control of quantum states for non-Hermitian fermions provides new methods of quantum control, and also sets the stage for exploring non-Hermitian topological states with SOC.

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confidence: 99%

Chiral control of quantum states in non-Hermitian spin-orbit-coupled fermions

Ren¹,

Liu²,

Zhao³

et al. 2021

Preprint

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“…So far, a wide spectrum of non-Hermitian phenomena, ranging from paritytime (PT)-symmetry breaking and non-Hermitian criticality [8][9][10], to non-Hermitian skin effects and non-Bloch topology [11][12][13][14][15][16][17][18], have been experimentally implemented and explored in quantum mechanical systems such as the single-photon interferometry network [19][20][21], cold atoms [22][23][24][25][26], nitrogen-vacancy centers [27,28], superconducting qubits [29], and trapped ions [30,31]. While most of these experiments investigate the single-particle aspects of the non-Hermitian physics, the interplay of non-Hermiticity and interaction is a fast-growing frontier with many open questions and fresh challenges [32][33][34][35][36].…”

Section: Introductionmentioning

confidence: 99%

Probing two-body exceptional points in open dissipative systems

Ding,

2021

Preprint

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We study two-body non-Hermitian physics in the context of an open dissipative system depicted by the Lindblad master equation. Adopting a minimal lattice model of a handful of interacting fermions with single-particle dissipation, we show that the non-Hermitian effective Hamiltonian of the master equation gives rise to two-body scattering states with state-and interaction-dependent parity-time transition. The resulting two-body exceptional points can be extracted from the tracepreserving density-matrix dynamics of the same dissipative system with three atoms. Our results not only demonstrate the interplay of PT symmetry and interaction on the exact few-body level, but also serve as a minimal illustration on how key features of non-Hermitian few-body physics can be probed in an open dissipative many-body system.

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“…During the past decade, PT -symmetric systems and the corresponding PT symmetry breaking have been experimentally realized and explored in various classical systems and quantum systems including quantum gas 28 , single spin system 29 , synthetic lattice 30 and single photon system 31 . Whereas the above experiments on quantum PT systems mainly focus on single particle physics [28][29][30][31] , recent theoretical studies have revealed intriguing physical properties with the interplay of the non-Hermitian effects and interactions [33][34][35][36][37][38] , such as enhanced sensitivity at exceptional points 33,34 , non-Hermitian superfluidity 35 and enhanced pairing superfluidity 36 , PT symmetric quantum critical phenomena 37,38 , anomalous slow dynamics in quantum criticality 39 , and nontrivial non-Hermitian many-body topological phases [40][41][42][43] . Particularly, several recent works reported experimental studies of dissipative many-body systems with controllable dissipation in bosonic optical lattices [44][45][46] , which have stimulated theoretical interests in exploring novel physical phenomena induced by the interplay between interaction and dissipation 2,[33][34][35][36][37][38][39][40][41][42]…”

Section: Introductionmentioning

confidence: 99%

Interaction induced dynamical $\mathcal{PT}$ symmetry breaking in dissipative Fermi-Hubbard models

Pan,

Wang,

Cui

et al. 2020

Preprint

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We investigate the dynamical properties of one-dimensional dissipative Fermi-Hubbard models, which are described by the Lindblad master equations with site-dependent jump operators. The corresponding non-Hermitian effective Hamiltonians with pure loss terms possess parity-time (PT ) symmetry after compensating an overall gain term. By solving the two-site Lindblad equation with fixed dissipation exactly, we find that the dynamics of rescaled density matrix shows an instability as the interaction increases over a threshold, which can be equivalently described in the scheme of non-Hermitian effective Hamiltonians. This instability is also observed in multi-site systems and closely related to the PT symmetry breaking accompanied by appearance of complex eigenvalues of the effective Hamiltonian. Moreover, we unveil that the dynamical instability of the anti-ferromagnetic Mott phase comes from the PT symmetry breaking in highly excited bands, although the low-energy effective model of the non-Hermitian Hubbard model in the strongly interacting regime is always Hermitian. We also provide a quantitative estimation of the time for the observation of dynamical PT symmetry breaking which could be probed in experiments.

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Enhanced Fermion Pairing and Superfluidity by an Imaginary Magnetic Field

Cited by 28 publications

References 39 publications

Chiral control of quantum states in non-Hermitian spin-orbit-coupled fermions

Chiral control of quantum states in non-Hermitian spin-orbit-coupled fermions

Probing two-body exceptional points in open dissipative systems

Interaction induced dynamical $\mathcal{PT}$ symmetry breaking in dissipative Fermi-Hubbard models

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