Two-mode Bose gas: Beyond classical squeezing

Bodet, Cédric; Estève, Jérôme; Oberthaler, Markus K.; Gasenzer, Thomas

doi:10.1103/physreva.81.063605

Cited by 15 publications

(19 citation statements)

References 64 publications

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“…Here the N particles, that are distributed between the two spatial modes, are described by a fictitious J = N/2 spin [36]. The two modes would represent the two states required to perform interferometry if that were our objective.…”

Section: Squeezed Statesmentioning

confidence: 99%

Bell inequality for pairs of particle-number-superselection-rule restricted states

2010

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Proposals for Bell-inequality tests on systems restricted by the particle-number-superselection rule often require operations that are difficult to implement in practice. In this article, we derive a Bell inequality, where measurements on pairs of states are used as a method to bypass this superselection rule. In particular, we focus on mode entanglement of an arbitrary number of massive particles and show that our Bell inequality detects the entanglement in an identical pair of states when other inequalities fail. However, as the number of particles in the system increases, the violation of our Bell inequality decreases due to the restriction in the measurement space caused by the superselection rule. This Bell test can be implemented using techniques that are routinely used in current experiments.

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Section: Squeezed Statesmentioning

confidence: 99%

Bell inequality for pairs of particle-number-superselection-rule restricted states

2010

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“…Both the experimental implementation of two-mode quantum entangled states and the two-site BH model are the ideal instruments to address the problem of the precision of the difference number and phase measurements [19,20]. In our work, we diagonalize the twosite BH Hamiltonian and evaluate the coherence visibility α, the Fisher information F , and the entanglement entropy S of the ground state.…”

Section: Introductionmentioning

confidence: 99%

Coherence and entanglement in the ground state of a bosonic Josephson junction: From macroscopic Schrödinger cat states to separable Fock states

et al. 2011

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We consider a bosonic Josephson junction made of N ultracold and dilute atoms confined by a quasi-onedimensional double-well potential within the two-site Bose-Hubbard model framework. The behavior of the system is investigated at zero temperature by varying the interatomic interaction from the strongly attractive regime to the repulsive one. We show that the ground state exhibits a crossover from a macroscopic Schrödinger-cat state to a separable Fock state through an atomic coherent regime. By diagonalizing the Bose-Hubbard Hamiltonian we characterize the emergence of the macroscopic cat states by calculating the Fisher information F , the coherence by means of the visibility α of the interference fringes in the momentum distribution, and the quantum correlations by using the entanglement entropy S. Both Fisher information and visibility are shown to be related to the ground-state energy by employing the Hellmann-Feynman theorem. This result, together with a perturbative calculation of the ground-state energy, allows simple analytical formulas for F and α to be obtained over a range of interactions, in excellent agreement with the exact diagonalization of the Bose-Hubbard Hamiltonian. In the attractive regime the entanglement entropy attains values very close to its upper limit for a specific interaction strength lying in the region where coherence is lost and self-trapping sets in.

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“…Substantial tunability of a has been demonstrated in the laboratory using Feshbach resonances. A particularly impressive example is [34], in which a for 7 Li was tuned between 0.53 pm and 10.6 µm (between 3.5 × 10 −7 a ho and 7 a ho , given the value of ω ho above).…”

Section: A the Many-body Double Well Hamiltonianmentioning

confidence: 99%

Number-squeezed and fragmented states of strongly interacting bosons in a double well

2017

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We present a systematic study of the phenomena of number squeezing and fragmentation for a repulsive Bose-Einstein condensate (BEC) in a three dimensional double well potential over a range of interaction strengths and barrier heights, including geometries that exhibit appreciable overlap in the one-body wavefunctions localized in the left and right wells. We compute the properties of the condensate with numerically exact, full dimensional path integral ground state (PIGS) Quantum Monte Carlo simulations and compare with results obtained from using two-and eight-mode truncated basis models. The truncated basis models are found to agree with the numerically exact PIGS simulations for weak interactions, but fail to correctly predict the amount of number squeezing and fragmentation exhibited by the PIGS simulations for strong interactions. We find that both number squeezing and fragmentation of the BEC show non-monotonic behavior at large values of interaction strength a. The number squeezing shows a universal scaling with the product of number of particles and interaction strength (N a) but no such universal behavior is found for fragmentation. Detailed analysis shows that the introduction of repulsive interactions not only suppresses number fluctuations to enhance number squeezing, but can also enhance delocalization across wells and tunneling between wells, each of which may suppress number squeezing. This results in a dynamical competition whose resolution shows a complex dependence on all three physical parameters defining the system: interaction strength, number of particles, and barrier height.

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Two-mode Bose gas: Beyond classical squeezing

Cited by 15 publications

References 64 publications

Bell inequality for pairs of particle-number-superselection-rule restricted states

Bell inequality for pairs of particle-number-superselection-rule restricted states

Coherence and entanglement in the ground state of a bosonic Josephson junction: From macroscopic Schrödinger cat states to separable Fock states

Number-squeezed and fragmented states of strongly interacting bosons in a double well

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