Phase-Matching Quantum Key Distribution

Ma, Xiongfeng; Zeng, Pei; Zhou, Hongyi

doi:10.1103/physrevx.8.031043

Cited by 262 publications

(313 citation statements)

References 46 publications

(94 reference statements)

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“…More recently, [28] proposed the twin-field (TF) QKD protocol, still characterized by an untrusted central node, and conjectured a square-root improvement in the key rate scaling. This scaling has been later on confirmed in [29,30] for two variants of the original scheme. The advantage of TF-QKD lies in the fact that it is designed to generate key bits from single-photon interference in the central node, thus naturally retaining the scaling with the square-root of the transmittance without the need to adapt to photon losses via sophisticated devices.…”

supporting

confidence: 53%

“…Since the original proposal, there has been an intense research activity to develop different versions of TF-QKD protocols equipped with their security proofs [29][30][31][32][33] as well as to investigate their experimental feasibility [34][35][36]. Among these protocols, the one that seems to deliver the higher secret ket rate [37] is that introduced in [33].…”

mentioning

confidence: 99%

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Practical decoy-state method for twin-field quantum key distribution

Grasselli

Curty

2019

New J. Phys.

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Twin-field (TF) quantum key distribution (QKD) represents a novel QKD approach whose principal merit is to beat the point-to-point private capacity of a lossy quantum channel, thanks to performing single-photon interference in an untrusted node. Indeed, recent security proofs of various TF-QKD type protocols have confirmed that the secret key rate of these schemes scales essentially as the square root of the transmittance of the channel. Here, we focus on the TF-QKD protocol introduced by Curty et al, whose secret key rate is nearly an order of magnitude higher than previous solutions. Its security relies on the estimation of the detection probabilities associated to various photon-number states through the decoy-state method. We derive analytical bounds on these quantities assuming that each party uses either two, three or four decoy intensity settings, and we investigate the protocol's performance in this scenario. Our simulations show that two decoy intensity settings are enough to beat the point-to-point private capacity of the channel, and that the use of four decoys is already basically optimal, in the sense that it almost reproduces the ideal scenario of infinite decoys. We also observe that the protocol seems to be quite robust against intensity fluctuations of the optical pulses prepared by the parties.The last few decades have witnessed major advancements in the field of quantum communication [1, 2], with quantum key distribution (QKD) [3-13] being its most developed application. Recent experiments over about 400 km of optical fibers [14,15] and over about 1000 km of satellite-to-ground links [16,17] demonstrated that QKD over long distances is possible. Despite such remarkable experimental achievements, the private capacity of point-to-point QKD is intrinsically limited by fundamental bounds [18,19]. These bounds state that in the high-loss regime the key rate scales basically linearly with the transmittance of the channel connecting the endusers Alice and Bob, i.e. it decreases exponentially with the total channel length. This imposes strict practical constraints on the possibility of achieving point-to-point QKD over arbitrary long distances.A way to overcome this limitation is to employ one or more intermediate nodes in the quantum channel connecting the parties. For instance, the use of quantum repeaters [20] yields a polynomial scaling of the communication efficiency with the distance [21]. Moreover, a quantum repeater scheme can be arbitrarily iterated along the quantum channel, thus increasing in principle the total communication distance between Alice and Bob as much as desired. Unfortunately, however, quantum repeaters are very challenging to build in practice with current technology: they either require quantum memories [20][21][22] or quantum error correction [23,24]. Of course, technology is improving, and quantum repeaters may become viable in the future.Other solutions, which attain a square-root improvement in the scaling of the key rate with respect to the transmittance of the channel, ...

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supporting

confidence: 53%

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confidence: 99%

Practical decoy-state method for twin-field quantum key distribution

Grasselli

Curty

2019

New J. Phys.

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“…Recently, some novel QKD schemes, such as twin‐field QKD (TFQKD) and phase‐matching QKD (PMQKD), have been proposed, which have raised significant interest in the quantum cryptography community, due to the provision of a secure key rate that scales with the square root of the communication channel transmission . These protocols present some connections with ours, even though their purpose is the establishment of a secret key between two parties, and not direct anonymous communication.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Experimental Two‐Way Communication with One Photon

et al. 2019

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Superposition of two or more states is one of the most fundamental concepts of quantum mechanics and provides a basis for several advantages offered by quantum information processing. This work reports the experimental demonstration of two‐way communication between two distant parties that can exchange only a single particle once, an impossible task in classical physics. This is achieved through preparation of a single photon in a coherent superposition of the two parties' locations. Furthermore, it is shown that this concept allows the parties to perform secure and anonymous quantum communication employing one particle per transmitted bit. These important features can lead to the realization of new quantum communication schemes, which are simultaneously anonymous, secure, and resource‐efficient.

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“…Because of these advantages, TF-QKD has attracted much attention worldwide since its proposal. Since a rigorous security proof is not provided in the original proposal, several papers have improved the protocol and provided security proof [6][7][8][9][10]. Also, recently there have been multiple reports of TF-QKD demonstrated experimentally [11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Simple method for asymmetric twin-field quantum key distribution

Wang

2020

New J. Phys.

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Twin-field quantum key distribution (TF-QKD) can beat the linear bound of repeaterless QKD systems. After the proposal of the original protocol, multiple papers have extended the protocol to prove its security. However, these works are limited to the case where the two channels have equal amount of loss (i.e. are symmetric). In a practical network setting, it is very likely that the channels are asymmetric due to e.g. geographical locations. In this paper we extend the 'simple TF-QKD' protocol to the scenario with asymmetric channels. We show that by simply adjusting the two signal states of the two users (and not the decoy states) they can effectively compensate for channel asymmetry and consistently obtain an order of magnitude higher key rate than previous symmetric protocol. It also can provide 2-3 times higher key rate than the strategy of deliberately adding fibre to the shorter channel until channels have equal loss (and is more convenient as users only need to optimize their laser intensities and do not need to physically modify the channels). We also perform simulation for a practical case with three decoy states and finite data size, and show that our method works well and has a clear advantage over prior art methods with realistic parameters. maintain the same channel loss for all users (and users might join/leave a network at arbitrary locations). If channels are asymmetric, for prior art protocols, users would either have to suffer from much higher quantumbit-error-rate (QBER) and hence lower key rate, or would have to deliberately add fibre to the shorter channel to compensate for channel asymmetry, which is inconvenient (since it requires physically modifying the channels) and also provides sub-optimal key rate.Similar limitation to symmetric channels have been observed in MDI-QKD. In [15], we have proposed a method to overcome this limitation, by allowing Alice and Bob to adjust their intensities (and use different optimization strategies for two decoupled bases) to compensate for channel loss, without having to physically adjust the channels. The method has also been successfully experimentally verified for asymmetric .In this work, we will apply our method to TF-QKD and show that it is possible to obtain good key rate through asymmetric channels by adjusting Alice's and Bob's intensities-in fact, we will show that, Alice and Bob only need to adjust their signal intensities to obtain optimal performance. We show that the security of the protocol is not affected, and that an order of magnitude higher (than symmetric protocol) or 2-3 times higher (than adding fibre) key rate can be achieved with the new method. Furthermore, we show with numerical simulation results that our method works well for both finite-decoy and finite-data case with practical parameters, making it a convenient and powerful method to improve the performance of TF-QKD through asymmetric channels in reality.While we use the same main idea of allowing Alice and Bob to use asymmetric intensities to compensate for asymmetric channe...

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Phase-Matching Quantum Key Distribution

Cited by 262 publications

References 46 publications

Practical decoy-state method for twin-field quantum key distribution

Practical decoy-state method for twin-field quantum key distribution

Experimental Two‐Way Communication with One Photon

Simple method for asymmetric twin-field quantum key distribution

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