Macroscopic bound entanglement in thermal graph states

Cavalcanti, Daniel; Aolita, Leandro; Ferraro, Alessandro; García-Sáez, Artur; Acín, Antonio

doi:10.1088/1367-2630/12/2/025011

Cited by 20 publications

(41 citation statements)

References 34 publications

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“…On the other hand, for some models, it has already been shown that there is still entanglement present in these models. This was first demonstrated for GHZ Hamiltonians [4], but has since been shown to exist in simpler models, such as for square lattices [5].…”

Section: Introductionmentioning

confidence: 92%

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Bound entanglement in tree graphs

Kay¹

2010

J. Phys. A: Math. Theor.

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In this paper, we discuss the entanglement properties of graph-diagonal states, with particular emphasis on calculating the threshold for the transition between the presence and absence of entanglement (i.e. the separability point). Special consideration is made of the thermal states of trees, including the linear cluster state. We characterise the type of entanglement present, and describe the optimal entanglement witnesses and their implementation on a quantum computer, up to an additive approximation. In the case of general graphs, we invoke a relation with the partition function of the classical Ising model, thereby intimating a connection to computational complexity theoretic tasks. Finally, we show that the entanglement is robust to some classes of local perturbations.

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Section: Introductionmentioning

confidence: 92%

“…Due to the numerical work of [5], we already expect that the critical temperature will not be significantly affected. In the case of a 1D chain, we can derive a recursion relation for the polynomial,…”

Section: Stability To Perturbationsmentioning

confidence: 99%

Bound entanglement in tree graphs

Kay¹

2010

J. Phys. A: Math. Theor.

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“…We demonstrate that in such a setup bound entangled states are produced for certain choices of temperature and coupling. The presence of undistillable entanglement in thermal finite-dimensional systems has been considered in [49].…”

Section: Multipartite Bound Entanglementmentioning

confidence: 99%

Beyond pure state entanglement for atomic ensembles

Stasińska

Paganelli²,

Sanpera³

2012

New J. Phys.

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We analyze multipartite entanglement between atomic ensembles within quantum matter-light interfaces. In our proposal, a polarized light beam crosses sequentially several polarized atomic ensembles impinging on each of them at a given angle α i . These angles are crucial parameters for shaping the entanglement since they are directly connected to the appropriate combinations of the collective atomic spins that are squeezed. We exploit such a scheme to go beyond the pure state paradigm proposing realistic experimental settings to address multipartite mixed state entanglement in continuous variables.

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“…Since system excitations are created by the Z Pauli operators, the thermal state is equivalent to the ground state under independent dephasing [13,17,18]. That is,…”

Section: Introductionmentioning

confidence: 99%

“…This difference comes from the fact that state (8) is not symmetric with respect to the exchange of qubits. At this point, the system becomes bound entangled [18]. If N Ap|BsBp = 0 = N Bp|ApBs , no entanglement can be extracted from the bipartitions A p |B s B p or B p |A p B s by local operations assisted by classical communication (LOCCs).…”

Section: Introductionmentioning

confidence: 99%

Linear-Optical Simulation of the Cooling of a Cluster-State Hamiltonian System

et al. 2014

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A measurement-based quantum computer could consist of a local-gapped Hamiltonian system, whose thermal states-at sufficiently low temperature-are universal resources for the computation. Initialization of the computer would correspond to cooling the system. We perform an experimental quantum simulation of such a cooling process with entangled photons. We prepare three-qubit thermal cluster states exploiting the equivalence between local dephasing and thermalization for these states. This allows us to tune the system's temperature by changing the dephasing strength. We monitor the entanglement as the system cools down and observe the transitions from separability to bound entanglement, and then to free entanglement. We also analyze the performance of the system for measurement-based single-qubit state preparation. These studies constitute a basic characterization of experimental cluster-state computation under imperfect conditions.

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Macroscopic bound entanglement in thermal graph states

Cited by 20 publications

References 34 publications

Bound entanglement in tree graphs

Bound entanglement in tree graphs

Beyond pure state entanglement for atomic ensembles

Linear-Optical Simulation of the Cooling of a Cluster-State Hamiltonian System

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