Entanglement and Spin Squeezing in Non-Hermitian Phase Transitions

Lee, Tony E.; Reiter, Florentin; Moiseyev, Nimrod

doi:10.1103/physrevlett.113.250401

Cited by 150 publications

(148 citation statements)

References 68 publications

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“…A recent study [31] reports the surprising finding that the non-Hermitian TACT model can realize slightly stronger SS than its Hermitian counterpart, which is counter intuitive as damping is always viewed as causing damage to quantum coherent processes like SS. Inspired by the desire for a better understanding of SS in nonHermitian models, we carried out this investigation of the non-Hermitian OAT model.…”

Section: Introductionmentioning

confidence: 99%

“…As in the non-Hermitian TACT model of Lee et al [31], a finite and tunable value for γ can be engineered through coupling of state | ↑ to an unstable auxiliary state |a . The Pauli operators in the above Eq.…”

Section: Steady Statementioning

confidence: 99%

“…Conditioned on the absence of a decay event [31], whose probability is given by P = e −N ↑ γt [32] for independent atomic decay as modeled here, one can remove the "real" decay term σ…”

Section: Steady Statementioning

confidence: 99%

See 2 more Smart Citations

Spin squeezing of the non-Hermitian one-axis twisting model

Jin

You

2015

Phys. Rev. A

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In the absence of decay, the conditional dynamics for an open system is often describable by a non-Hermitian Hamiltonian. This study investigates spin squeezing (SS) in non-Hermitian one-axis twisting (OAT) model. Somewhat surprisingly, SS close to the limit of Hermitian two-axis counter twisting (TACT) Hamiltonian is achievable for some parameters, which significantly improves upon the optimal value realizable by Hermitian OAT model. The drawback is like with all conditional schemes, it takes on average longer time to evolve into steady state, and the probability of no decay or success decreases as number of atoms (spins) increases. The result above for steady state SS in non-Hermitian OAT Hamiltonian is thus limited to small systems. For other parameter regimes, however, desirable SS arrives dynamically before steady state is achieved, with greatly shortened evolution time and enhanced probability of success, while still remain significantly improved over the limit of Hermitian OAT.

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Section: Introductionmentioning

confidence: 99%

Section: Steady Statementioning

confidence: 99%

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Spin squeezing of the non-Hermitian one-axis twisting model

Jin

You

2015

Phys. Rev. A

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“…It seems that the non hermiticity is needed. Futur works must be dedicated to find a more realistic model exhibiting quantum chimera states, but we can imagine experimental realizations of some quantum chimera models with trapped ions and cavity QED, since these situations can be modelled by non-hermitian effective Hamiltonians as in [20,21]. Unfortunately, in these cases the effective Hamiltonian is valid only between two quantum jumps.…”

Section: Resultsmentioning

confidence: 99%

“…We say that H is quasi-hermitian 1 . H can be viewed as the effective Hamiltonian of a long range coupling Heisenberg spin chain in contact with an environment (examples of non-hermitian effective Hamiltonians can be found in [20,21]). …”

Section: The Modelmentioning

confidence: 99%

Quantum chimera states

Viennot

Aubourg

2016

Physics Letters A

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We study a theoretical model of closed quasi-hermitian chain of spins which exhibits quantum analogues of chimera states, i.e. long life classical states for which a part of an oscillator chain presents an ordered dynamics whereas another part presents a disordered dynamics. For the quantum analogue, the chimera behavior deals with the entanglement between the spins of the chain. We discuss the entanglement properties, quantum chaos, quantum disorder and semiclassical similarity of our quantum chimera system. The quantum chimera concept is novel and induces new perspectives concerning the entanglement of multipartite systems.

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Enhancement of Steady Quantum Entanglement and Directional Controllability of Quantum Steering in Cavity Magnetic Hybrid Systems

et al. 2023

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Quantum entanglement (QE) and quantum steering (QS) are of importance for quantum information processing and computation. Though there are several schemes proposed for their realization, how to increase their degrees encounters a great challenge. In the present manuscript, it is proposed to enhance steady QE and control Gaussian QS for two magnons using a two-photon field acting on either magnon. The cavity-magnetic hybrid system consists of a microwave cavity in which two identical Yttrium-iron-garnet spheres are placed and the cavity is driven by a Josephson parametric amplifier (JPA) so as to generate steady QE and control Gaussian QS for the two Kittel modes. Besides, a two-photon driving field acting on either magnon in order to enhance the degree of QE and the ability of QS. The best condition to maximum entanglement and steering degrees for the two magnon modes at 𝜺 ≈ 0.8 MHz and r ≈ 2 is found via the competitive relationship between the two-photon driving and JPA. Furthermore, it is revealed that steering direction for the two magnons can be controlled not only by the ratio between the two photon-magnon coupling parameters but also by the two-photon driving field, making controllable steering direction become easier.

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Entanglement and Spin Squeezing in Non-Hermitian Phase Transitions

Cited by 150 publications

References 68 publications

Spin squeezing of the non-Hermitian one-axis twisting model

Spin squeezing of the non-Hermitian one-axis twisting model

Quantum chimera states

Enhancement of Steady Quantum Entanglement and Directional Controllability of Quantum Steering in Cavity Magnetic Hybrid Systems

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