Two-axis-twisting spin squeezing by multipass quantum erasure

Wang, Mingfeng; Qu, Weizhi; Li, Pengxiong; Bao, Han; Vuletić, Vladan; Xiao, Yanhong

doi:10.1103/physreva.96.013823

Cited by 32 publications

(22 citation statements)

References 33 publications

(72 reference statements)

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“…Recently, Wang et al [61] have shown that one can erase the remaining back-action of the two-pass scheme in a three-pass configuration to achieve unitary spinsqueezing of an atomic ensemble. With phase shifts φ ij between passes i and j, the full master equation in this case readsρ Setting φ 12 = φ 23 = φ, the solution is found to be φ = ±2π/3.…”

Section: Unconditional Squeezing Of a Single Oscillatormentioning

confidence: 99%

Remote Hamiltonian interactions mediated by light

et al. 2019

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We address a fundamental question of quantum optics: Can a beam of light mediate coherent Hamiltonian interactions between two distant quantum systems? This is an intriguing question whose answer is not a priori clear, since the light carries away information about the systems and might be subject to losses, giving rise to intrinsic decoherence channels associated with the coupling.Our answer is affirmative and we derive a particularly simple sufficient condition for the interactions to be Hamiltonian: The light field needs to interact twice with the systems and the second interaction has to be the time reversal of the first.We demonstrate that, even in the presence of significant optical loss, coherent interactions can be realized and generate substantial amounts of entanglement between the systems. Our method is directly applicable for building hybrid quantum systems, with relevant applications in the fields of optomechanics and atomic ensembles. * thomas.karg@unibas.ch † philipp.treutlein@unibas.ch framework was applied fruitfully in the description of cascaded optical cavities [8], atomic ensembles interacting arXiv:1901.06891v2 [quant-ph]

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Section: Unconditional Squeezing Of a Single Oscillatormentioning

confidence: 99%

Remote Hamiltonian interactions mediated by light

et al. 2019

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“…In these works the entangled state that is produced can be described within this approximation as a two-mode squeezed state. However, due to the fundamentally different nature of the spins to modes, it is well known that different dynamics can result for long evolution times, observed in effects such as oversqueezing [24][25][26][27][28][29]. Entanglement between different spatial regions of a single BEC was experimentally observed [30][31][32].…”

Section: Introductionmentioning

confidence: 99%

Two-axis two-spin squeezed states

Kitzinger

Chaudhary

Kondappan

et al. 2020

Phys. Rev. Research

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The states generated by the two-spin generalization of the two-axis countertwisting Hamiltonian are examined. We analyze the behavior at both short and long timescales, by calculating various quantities such as squeezing, spin expectation values, probability distributions, entanglement, Wigner functions, and Bell correlations. In the limit of large spin ensembles and short interaction times, the state can be described by a two-mode squeezed vacuum state; for qubits, Bell state entanglement is produced. We find that the Hamiltonian approximately produces two types of spin Einstein-Podolsky-Rosen (EPR) states, and the time evolution produces aperiodic oscillations between them. In a similar way to the basis invariance of Bell states and two-mode squeezed vacuum states, the Fock state correlations of spin EPR states are basis invariant. We find that it is possible to violate a Bell inequality with such states, although the violation diminishes with increasing ensemble size. Effective methods to detect entanglement are also proposed, and formulas for the optimal times to enhance various properties are calculated.

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“…Note that the control problem considered in this paper is not contained in the framework where the superiority of CF over MF (or the equivalency of CF and MF) has been proved [20, 24-26, 28, 33]. Also the proposed scheme is a sort of reservoir engineering but is different from the other approaches [35][36][37][38][39][40][41][42], in that it relies on a novel reservoir composed of the series of dispersive and dissipative couplings, inspired by the MF control composed of the QND measurement and the subsequent filtering process.…”

Section: Introductionmentioning

confidence: 99%

Replacing measurement feedback with coherent feedback for quantum state preparation

Kashiwamura

Yamamoto

2018

Phys. Rev. A

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The measurement-feedback is a versatile and powerful means, although its performance must be limited by several practical imperfections resulting from classical components. This paper shows that, for some typical quantum feedback control problems for state preparation (stabilization of a qubit or a qutrit, spin squeezing, and Fock state generation), the classical feedback operation can be replaced by a fully quantum one such that the state autonomously dissipates into the target or a state close to the target. The main common feature of the proposed quantum operation, which is called the coherent feedback, is that it is composed of the series of dispersive and dissipative couplings inspired by the corresponding measurement-feedback scheme.

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Two-axis-twisting spin squeezing by multipass quantum erasure

Cited by 32 publications

References 33 publications

Remote Hamiltonian interactions mediated by light

Remote Hamiltonian interactions mediated by light

Two-axis two-spin squeezed states

Replacing measurement feedback with coherent feedback for quantum state preparation

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