Entanglement distillation for continuous variables in a thermal environment: Effectiveness of a non-Gaussian operation

Lee, Jaehak; Nha, Hyunchul

doi:10.1103/physreva.87.032307

Cited by 28 publications

(27 citation statements)

References 31 publications

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“…Single-photon-level non-Gaussian operations such as photon subtraction [3][4][5][6][7][8][9][10][11][12][13][14][15], photon addition [4,12,16,17] and a coherent superposition of addition and subtraction [18][19][20], here termed photon replacement, are powerful tools which, under certain conditions, can be used to increase entanglement. In the case of photon subtraction, the entanglement-enhancing capability has been experimentally demonstrated [21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Directly comparing entanglement-enhancing non-Gaussian operations

Bartley

2015

New J. Phys.

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Single-photon-level non-Gaussian operations-photon addition, photon subtraction, and their coherent superposition-are powerful tools with which to increase entanglement in continuous-variable optical states. Although such operations are typically not deterministic, there may be other advantages such as noiseless manipulation. Therefore, to fully account for the efficacy of a particular non-Gaussian operation in a practical scenario, we develop figures of merit which trade off the advantages of such protocols against their success probability. Specifically, we define 'entanglement enhancement rate' as the increase in entanglement per trial of a generic non-Gaussian operation on a two-mode squeezed vacuum (TMSV) state. We consider states generated by photon-subtraction, photon-addition and a coherent superposition of subtraction and addition. We compare each strategy when applied to one or both modes of a TMSV state, and also in the presence of channel losses prior to the operation. In many cases, additional properties are analytically calculable, including excess noise arising from the operation and the fidelity of the resulting states to particular Gaussian and non-Gaussian states. Finally, by incorporating loss, we derive optimal interaction parameters for each non-Gaussian operation which maximize the effectiveness of the particular protocol under investigation.

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Section: Introductionmentioning

confidence: 99%

Directly comparing entanglement-enhancing non-Gaussian operations

Bartley

2015

New J. Phys.

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“…Many studies have shown that teleportation fidelity can be improved by non-Gaussian manipulation on Gaussian entangled states [18][19][20][21][22][23]. In particular, it was shown that a two-mode Gaussian state which does not beat nocloning limit can overcome it by applying non-Gaussian operations [19].…”

Section: B Non-gaussian Manipulationmentioning

confidence: 99%

“…In a variety of studies such as entanglement distillation [17][18][19][20][21][22][23] and robustness of entanglement [24,25], teleportation fidelity has been employed as an operational measure of entanglement to test if an entangled state at hand is a useful resource. For multipartite communications, it is important to know how useful a given multipartite entangled state is in view of performance achieved individually by each pair of users and performance achieved collectively by all users.…”

Section: Introductionmentioning

confidence: 99%

Monogamy relation in multipartite continuous-variable quantum teleportation

Lee

Park

et al. 2016

Phys. Rev. A

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Quantum teleportation (QT) is a fundamentally remarkable communication protocol that also finds many important applications for quantum informatics. Given a quantum entangled resource, it is crucial to know to what extent one can accomplish the QT. This is usually assessed in terms of output fidelity, which can also be regarded as an operational measure of entanglement. In the case of multipartite communication when each communicator possesses a part of N -partite entangled state, not all pairs of communicators can achieve a high fidelity due to monogamy property of quantum entanglement. We here investigate how such a monogamy relation arises in multipartite continuous-variable (CV) teleportation particularly using a Gaussian entangled state. We show a strict monogamy relation, i.e. a sender cannot achieve a fidelity higher than optimal cloning limit with more than one receiver. While this seems rather natural owing to the no-cloning theorem, a strict monogamy relation still holds even if the sender is allowed to individually manipulate the reduced state in collaboration with each receiver to improve fidelity. The local operations are further extended to non-Gaussian operations such as photon subtraction and addition, and we demonstrate that the Gaussian cloning bound cannot be beaten by more than one pair of communicators. Furthermore we investigate a quantitative form of monogamy relation in terms of teleportation capability, for which we show that a faithful monogamy inequality does not exist.

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“…When the operations succeed, they amplify an optical field with an amount of noise less than that required as the quantum limit [29][30][31][32][33][34][35]. For two mode systems, they can also distill quantum entanglement of bipartite CV systems even for Gaussian states [36][37][38][39][40] under a noisy environment [38,41] beyond the No-Go theorem of Gaussian regime [42][43][44] and enhance the violation of local realism [45][46][47][48][49]. They can also be useful for quantum communication, e.g., by enhancing the fidelity of the quantum teleportation [39,[50][51][52][53][54].…”

Section: Introductionmentioning

confidence: 99%

Enhanced multipartite quantum correlation by non-Gaussian operations

Kim

Nha

2013

Phys. Rev. A

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We study how conditional photon operations can affect multipartite quantum correlations, specifically nonlocality and entanglement, of the continuous variable GHZ states. We find that the violation of the Mermin-Klyshko inequality revealing the multipartite nonlocality can be made stronger with photon subtraction applied on each mode of the original GHZ states, particularly in a weak squeezing regime. Photon addition applied on local modes also turns out to enhance the degree of multipartite nonlocality in a broad range of parameters. We further investigate the effects of the photon operations on the degree of multipartite entanglement by looking into the Gaussian tangle, the fidelity of teleportation network, and the quadrature correlations. We find that photon subtraction applied on two modes enhances those entanglement characteristics in a practical squeezing regime while there is no improvement made by photon addition.

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Entanglement distillation for continuous variables in a thermal environment: Effectiveness of a non-Gaussian operation

Cited by 28 publications

References 31 publications

Directly comparing entanglement-enhancing non-Gaussian operations

Directly comparing entanglement-enhancing non-Gaussian operations

Monogamy relation in multipartite continuous-variable quantum teleportation

Enhanced multipartite quantum correlation by non-Gaussian operations

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