All-photonic quantum repeaters

Azuma, Koji; Tamaki, Kiyoshi; Lo, Hoi Kwong

doi:10.1038/ncomms7787

Cited by 463 publications

(545 citation statements)

References 58 publications

(420 reference statements)

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“…The growth and slow decay along the line η 0 = 1 here is regarded as a concrete example of such an advantage invoking the PLOB bound. The slow decay has also been observed for the codes (3,2) and (3,3), although it does not reach the long distances over 1000km (There, the longest distance to surpass the PLOB bound is achieved with rather lower unit transmission, η 0 ∼ 0.85). Therefore, the graphs in Figs.…”

Section: B Other Small-block Codes [(32)(33)(43)]mentioning

confidence: 92%

“…The shape of the areas depends on both the block size and the error rate. Figure 12 shows the area to beat the PLOB bound for the case of the (4,3) code. An interesting feature observed in this code is that the area at a higher unit transmission grows significantly towards longer distance, and covers relatively wide range of η 0 and L tot , although it still require an order of 10 −3 physical error rate.…”

Section: B Other Small-block Codes [(32)(33)(43)]mentioning

confidence: 99%

“…To explore the possibility of quantum communication schemes over a long distance [1][2][3][4][5], an essential question is whether the secret key generation rate of quantum key distribution (QKD) with the help of intermediate stations could be better than any key generation scheme without intermediate stations. A clear criterion for this is to surpass the TakeokaGuha-Wilde (TGW) bound [6,7].…”

Section: Introductionmentioning

confidence: 99%

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Role of syndrome information on a one-way quantum repeater using teleportation-based error correction

et al. 2016

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We investigate a quantum repeater scheme for quantum key distribution based on the work by Muralidharan et al., Phys. Rev. Lett. 112, 250501 (2014). Our scheme extends that work by making use of error syndrome measurement outcomes available at the repeater stations. We show how to calculate the secret key rates for the case of optimizing the syndrome information, while the known key rate is based on a scenario of coarse-graining the syndrome information. We show that these key rates can surpass the Pirandola-Laurenza-Ottaviani-Banchi bound on secret key rates of direct transmission over lossy bosonic channels.

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Section: B Other Small-block Codes [(32)(33)(43)]mentioning

confidence: 92%

Section: B Other Small-block Codes [(32)(33)(43)]mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Role of syndrome information on a one-way quantum repeater using teleportation-based error correction

et al. 2016

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“…There are many quantum repeater schemes proposed so far [6][7][8][9][10][11]. Considering the experimental capabilities, the memory-photon entanglement based schemes [6] are much more feasible than the error correction based schemes [6][7][8][9][10][11]. Towards a first quantum repeater based on memory-photon entanglement, significant progresses have made in improving performances of the building blocks [6].…”

Section: Pacs Numbersmentioning

confidence: 99%

An efficient quantum light–matter interface with sub-second lifetime

Yang¹,

Wang²,

Bao³

et al. 2016

Nature Photon

185

182

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Quantum repeater holds the promise for scalable long-distance quantum communication. Towards a first quantum repeater based on memory-photon entanglement, significant progresses have made in improving performances of the building blocks. Further development is hindered by the difficulty of integrating key capabilities such as long storage time and high memory efficiency into a single system. Here we report an efficient light-matter interface with sub-second lifetime by confining laser-cooled atoms with 3D optical lattice and enhancing the atom-photon coupling with a ring cavity. An initial retrieval efficiency of 76(5)% together with an 1/e lifetime of 0.22(1) s have been achieved simultaneously, which already support sub-Hz entanglement distribution up to 1000 km through quantum repeater. Together with an efficient telecom interface and moderate multiplexing, our result may enable a first quantum repeater system that beats direct transmission in the near future. PACS numbers:Quantum communication [1, 2] relies on photon transimission over long distance. Direct transmission is limited to moderate distances (less than 500 km [3,4]) due to exponential decay of photons. Quantum repeater [5] is an ultimate solution to go significantly beyond this limitation. There are many quantum repeater schemes proposed so far [6][7][8][9][10][11]. Considering the experimental capabilities, the memory-photon entanglement based schemes [6] are much more feasible than the error correction based schemes [6][7][8][9][10][11]. Towards a first quantum repeater based on memory-photon entanglement, significant progresses have made in improving performances of the building blocks [6]. Further development is hindered by the difficulty of integrating key capabilities such as long storage time [12] and high memory efficiency [13] into a single system. So far, storage lifetime has been improved to the sub-second regime for single excitations in an atomic ensemble [12,14] and to the sub-minute regime for classical light storage [15], nevertheless, storage efficiency in these experiments is typically very low (∼16%). If we define a threshold of 50% for the memory efficiency, the longest storage time is limited to 1.2 ms [16], which is far away from the second regime requirement [6] of a quantum repeater. Memory efficiency is essentially important as it intervenes in every entanglement swapping operation between adjacent quantum repeater nodes. According to theoretical estimations [6], 1% increase of retrieval efficiency can improve long-distance entanglement distribution rate by 10%∼14%.In this paper, we report an efficient quantum memory with sub-second regime lifetime by making use of a 3D optical lattice confined atomic ensemble inside a ring cavity. The quantum memory is nonclassically correlated with a single photon, thus forms a light-matter interface for quantum repeaters [6,17]. Optical lattice limits atomic motion in all direction thus suppresses various motion-induced decoherence, and ring cavity enhances atom-photon coupling thus imp...

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“…Quantum repeater technology, in particular the ones built using quantum memories, has been a subject of intense investigation in recent years 10,11 ; however, an operational demonstration of a quantum repeater has proven extremely challenging and is yet to be conducted (note that some repeater protocols without quantum memory have been proposed recently 12,13 ; however, their implementation is still challenging).…”

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confidence: 99%

Fundamental rate-loss tradeoff for optical quantum key distribution

2014

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Since 1984, various optical quantum key distribution (QKD) protocols have been proposed and examined. In all of them, the rate of secret key generation decays exponentially with distance. A natural and fundamental question is then whether there are yet-to-be discovered optical QKD protocols (without quantum repeaters) that could circumvent this rate-distance tradeoff. This paper provides a major step towards answering this question. Here we show that the secret key agreement capacity of a lossy and noisy optical channel assisted by unlimited two-way public classical communication is limited by an upper bound that is solely a function of the channel loss, regardless of how much optical power the protocol may use. Our result has major implications for understanding the secret key agreement capacity of optical channels-a long-standing open problem in optical quantum information theory-and strongly suggests a real need for quantum repeaters to perform QKD at high rates over long distances.

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All-photonic quantum repeaters

Cited by 463 publications

References 58 publications

Role of syndrome information on a one-way quantum repeater using teleportation-based error correction

Role of syndrome information on a one-way quantum repeater using teleportation-based error correction

An efficient quantum light–matter interface with sub-second lifetime

Fundamental rate-loss tradeoff for optical quantum key distribution

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