Entanglement purification for quantum communication

An experimental scheme for concentrating entanglement in partially entangled photon pairs is proposed. In this scheme, two separated parties obtain one maximally entangled photon pair from previously shared two partially entangled photon pairs by local operations and classical communication. A practical realization of the proposed scheme is discussed, which uses imperfect photon detectors and spontaneous parametric down-conversion as a photon source. This scheme also works for purifying a class of mixed states.

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“…After the submission of this paper, another type of purification scheme for photon pairs was proposed by Pan et al [20].…”

Section: Discussionmentioning

confidence: 99%

Concentration and purification scheme for two partially entangled photon pairs

2001

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“…* email: wang@qci.jst.go.jp 1 With the discovery of maximal polarization entangled state with the spontaneous parametric down conversion(SPDC) [6], linear optics method has been perhaps the most powerful tool for realizing the entanglement based quantum tasks. So far many of the tasks have been proposed or demonstrated with linear optics, such as quantum teleportation [7], universal quantum cloning [8], quantum U-NOT operation [9], quantum entanglement concentration and purification [10,11] and destructive quantum logic gate [12]. However, none of the quantum error correction code has been experimentally realized so far [13].…”

Section: Introductoinmentioning

confidence: 99%

“…So far many of the tasks have been proposed or demonstrated with linear optics, such as quantum teleportation [7], universal quantum cloning [8], quantum U-NOT operation [9], quantum entanglement concentration and purification [10,11] and destructive quantum logic gate [12]. However, none of the quantum error correction code has been experimentally realized so far [13].…”

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confidence: 99%

Quantum error-rejection code with spontaneous parametric down-conversion

Wang

2004

Phys. Rev. A

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We propose a linear optical scheme to transmit an unknown qubit robustly over bit-flip-error channel. To avoid the technical difficulty of the standard quantum error correction code, our scheme is based on the concept of errorrejection. The whole scheme is based on currently existing technology. I. INTRODUCTOINAn unknown qubit can be sent to a remote party robustly through a noisy channel if we use the quantum error correction code (QECC) [1][2][3], which plays a very important role in quantum computation and information [4]. The main idea there is first to encode the unknown qubit to an entangled state of many qubits and after the remote party receives this quantum code, he first decodes it and then obtains the original state faithfully. This is very different from the classical error correction since the unknown qubit in principle can not be copied [5] or observed exactly therefore the simple repetition code as used in classical coding is not applicable here. * email: wang@qci.jst.go.jp 1 With the discovery of maximal polarization entangled state with the spontaneous parametric down conversion(SPDC) [6], linear optics method has been perhaps the most powerful tool for realizing the entanglement based quantum tasks. So far many of the tasks have been proposed or demonstrated with linear optics, such as quantum teleportation [7], universal quantum cloning [8], quantum U-NOT operation [9], quantum entanglement concentration and purification [10,11] and destructive quantum logic gate [12]. However, none of the quantum error correction code has been experimentally realized so far [13]. Realizing either Shor's 9-qubit code, Steane's 7-qubit code or the 5-qubit code [3] is technically challenging by our current technology. All of them are based on the quantum entangled state with more than 5 qubits. This requires at least 3 pairs to be emitted by SPDC [6]. In a paper two years ago [15], the optical realization of quantum error rejection code over the bit-flip-error channel is considered. It was shown there [15] that the controlled-NOT operation in quantum error correction can be done probabilistically by a polarizing beam splitter and one can transfer a qubit robustly over a bit flip channel by teleportation. However, that scheme is based on the resource of three-photon GHZ state which is thought of as a type of impractical resource by our currently existing technology [15]. In particular, it was pointed in Ref. [15] that the post selection method given by [16,17] cannot be applied to the scheme proposed in [15].In this paper, we propose a realization of quantum error rejection code over bit-flip-error channel with currently existing devices and resources in linear optics. II. 2-BIT BIT-FLIP ERROR REJECTION CODETo test the main points of the quantum error correction code we shall consider a simpler case here: transmitting an unknown qubit robustly over the bit flip channel using a smaller quantum code. We assume no phase flip noise for channel. Note that even in such a case there is no trivial way to complete...

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“…Since Bennett et al [24] proposed the first entanglement purification protocol (EPP) in 1996, many works were focused on it and many important EPPs have been proposed, resorting to different physical systems [24][25][26][27][28][29][30][31][32][33][34][35][36][37]. Compared with an EPP, an entanglement concentration protocol (ECP) is usually more efficient for the two parties in quantum communication, say Alice and Bob, to distill some maximally entangled systems from an ensemble in a less-entangled pure state.…”

Section: Introductionmentioning

confidence: 99%

Optimal multipartite entanglement concentration of electron-spin states based on charge detection and projection measurements

Ren

Wei

et al. 2013

Quantum Inf Process

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We propose an optimal entanglement concentration protocol (ECP) for nonlocal N-electron systems in a partially entangled pure state, resorting to charge detection and the projection measurement on an additional electron. For each nonlocal N-electron system, one party in quantum communication, say Alice first entangles it with an additional electron, and then she projects the additional electron into an orthogonal basis for dividing the N-electron systems into two groups. In the first group, the N parties obtain a subset of N-electron systems in a maximally entangled state directly. In the second group, they obtain some less-entangled N-electron systems which are the resource for the entanglement concentration in the next round. By iterating the entanglement concentration process several times, the present ECP has the maximal success probability, the theoretical limit of an ECP as it just equals to the entanglement of the partially entangled state, far higher than others, without resorting to a collective unitary evolution.

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Entanglement purification for quantum communication

Cited by 742 publications

References 30 publications

Concentration and purification scheme for two partially entangled photon pairs

Concentration and purification scheme for two partially entangled photon pairs

Quantum error-rejection code with spontaneous parametric down-conversion

Optimal multipartite entanglement concentration of electron-spin states based on charge detection and projection measurements

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