Nonlocality and entanglement for symmetric states

Wang, Zizhu; Markham, Damian

doi:10.1103/physreva.87.012104

Cited by 20 publications

(19 citation statements)

References 67 publications

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“…Moreover, the nonlocality of symmetric pure qubit states is elegantly captured by a single Bell inequality [20]. The nonlocality of the simplest Dicke states, featuring a single excitation (the so-called W -states), has been widely discussed [21][22][23][24][25][26][27], in particular in the context of optical Bell tests based on single photon entanglement [28][29][30]. Notably, the possibility of self-testing the W state has been recently demonstrated [31,32].…”

Section: Introductionmentioning

confidence: 99%

Nonlocality ofWand Dicke states subject to losses

et al. 2015

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We discuss the nonlocality of the W and the Dicke states subject to losses. We consider two noise models, namely loss of excitations and loss of particles, and investigate how much loss can be tolerated such that the final state remains nonlocal. This leads to a measure of robustness of the nonlocality of Dicke states, with a clear physical interpretation. Our results suggest that the relation between nonlocality and entanglement of Dicke states is not monotonous.

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Section: Introductionmentioning

confidence: 99%

Nonlocality ofWand Dicke states subject to losses

et al. 2015

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“…Therefore, although the mapping of the single-resonator state to a W state does not increase the lifetime of the state itself, the entanglement that is generated by the process is well suited to the many-resonator regime. Further, it is of particular use for tests of nonlocality that utilize large-scale W states [22,23]. Another significant aspect of our protocol is that when jc in i are coherent states (with a sufficiently large amplitude), the protocol outputs entangled coherent states (ECSs) [24,25], which are of both fundamental and applied significance in their own right [25][26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

Deterministic Many-ResonatorWEntanglement of Nearly Arbitrary Microwave States via Attractive Bose-Hubbard Simulation

2013

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Multipartite entanglement of large numbers of physically distinct linear resonators is of both fundamental and applied interest, but there have been no feasible proposals to date for achieving it. At the same time, the Bose-Hubbard model with attractive interactions (ABH) is theoretically known to have a phase transition from the superfluid phase to a highly entangled nonlocal superposition, but observation of this phase transition has remained out of experimental reach. In this theoretical work, we jointly address these two problems by (1) proposing an experimentally accessible quantum simulation of the ABH phase transition in an array of tunably coupled superconducting circuit microwave resonators and (2) incorporating the simulation into a highly scalable protocol that takes as input any microwave-resonator state with negligible occupation of number states j0i and j1i and nonlocally superposes it across the whole array of resonators. The large-scale multipartite entanglement produced by the protocol is of the W type, which is well known for its robustness. The protocol utilizes the ABH phase transition to generate the multipartite entanglement of all of the resonators in parallel, and is therefore deterministic and permits an increase in resonator number without any increase in protocol complexity; the number of resonators is limited instead by system characteristics such as resonator-frequency disorder and inter-resonator coupling strength. Only one local and two global controls are required for the protocol. We numerically demonstrate the protocol with realistic system parameters and estimate that current experimental capabilities can realize the protocol with high fidelity for greater than 40 resonators. Because superconducting-circuit microwave resonators are capable of interfacing with other devices and platforms such as mechanical resonators and (potentially) optical fields, this proposal provides a route toward large-scale W-type entanglement in those systems as well.

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“…1(b). This state is called the W state [25,42,43] because of its resemblance with the W state of entangled qubits [44].…”

Section: W Phasementioning

confidence: 99%

Phases of the disordered Bose-Hubbard model with attractive interactions

2021

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We study the quantum ground-state phases of the one-dimensional disordered Bose-Hubbard model with attractive interactions, realized by a chain of superconducting transmon qubits or cold atoms. We map the phase diagram using perturbation theory and exact diagonalization. Compared to the repulsive Bose-Hubbard model, the quantum ground-state behavior is dramatically different. At strong disorder of the on-site energies, all the bosons localize into the vicinity of a single site, contrary to the Bose glass behavior of the repulsive model. At weak disorder, depending on hopping, the ground state is either superfluid or a W state, which is a multisite and multiparticle entangled superposition of states where all the bosons occupy a single site. We show that the robustness of the W phase against disorder diminishes as the total number of bosons increases.

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Nonlocality and entanglement for symmetric states

Cited by 20 publications

References 67 publications

Nonlocality ofWand Dicke states subject to losses

Nonlocality ofWand Dicke states subject to losses

Deterministic Many-ResonatorWEntanglement of Nearly Arbitrary Microwave States via Attractive Bose-Hubbard Simulation

Phases of the disordered Bose-Hubbard model with attractive interactions

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