Breaking the Rate-Loss Bound of Quantum Key Distribution with Asynchronous Two-Photon Interference

Quantum key distribution — the establishment of information-theoretically secure keys based on quantum physics — is mainly limited by its practical performance, which is characterised by the dependence of the key rate on the channel transmittance R(η). Recently, schemes based on single-photon interference have been proposed to improve the key rate to $$R=O(\sqrt{\eta })$$ R = O ( η ) by overcoming the point-to-point secret key capacity bound with interferometers. Unfortunately, all of these schemes require challenging global phase locking to realise a stable long-arm single-photon interferometer with a precision of approximately 100 nm over fibres that are hundreds of kilometres long. Aiming to address this problem, we propose a mode-pairing measurement-device-independent quantum key distribution scheme in which the encoded key bits and bases are determined during data post-processing. Using conventional second-order interference, this scheme can achieve a key rate of $$R=O(\sqrt{\eta })$$ R = O ( η ) without global phase locking when the local phase fluctuation is mild. We expect this high-performance scheme to be ready-to-implement with off-the-shelf optical devices.

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“…Note added to proof. After we submitted our work for reviewing, we became aware of a relevant work by Xie et al 59…”

Section: Methodsmentioning

confidence: 99%

Mode-pairing quantum key distribution

Zeng

Zhou

et al. 2022

Nat Commun

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“…We propose a system that uses an adaptive technique in Appendix B , while we need to investigate the specific performance in our scheme. At the same time, we will consider using asynchronous time multiplexing technology [ 34 , 35 ], which idea is based on adaptive techniques, to further improve our scheme through enhancing the secure key rate under multi-user scenarios.…”

Section: Secure Key Ratementioning

confidence: 99%

Multi-User Measurement-Device-Independent Quantum Key Distribution Based on GHZ Entangled State

Hua

Guo

2022

Entropy

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As a multi-particle entangled state, the Greenberger–Horne–Zeilinger (GHZ) state plays an important role in quantum theory and applications. In this study, we propose a flexible multi-user measurement-device-independent quantum key distribution (MDI-QKD) scheme based on a GHZ entangled state. Our scheme can distribute quantum keys among multiple users while being resistant to detection attacks. Our simulation results show that the secure distance between each user and the measurement device can reach more than 280 km while reducing the complexity of the quantum network. Additionally, we propose a method to expand our scheme to a multi-node with multi-user network, which can further enhance the communication distance between the users at different nodes.

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“…In the experiment, we utilize four-intensity decoy-state quantum key distribution to generate the secret keys for the QDS processes in our QBA protocol [52]. We note that networks using any quantum key distribution protocols [53][54][55][56][57][58] can serve as the basis for our QBA scheme. There are five independent users, A, B, C, D and E. The secret keys of different pairwise users are pre-generated in the laboratory via a fibre spool.…”

Section: Experimental Implementationmentioning

confidence: 99%

Beating the fault-tolerance bound and security loopholes for Byzantine agreement with a quantum solution

Weng¹,

Gao²,

Yu³

et al. 2022

Preprint

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Byzantine agreement, the underlying core of blockchain, aims to make every node in a decentralized network reach consensus. However, the classical Byzantine agreement faces two major problems. One is the 1/3 fault-tolerance bound, which means the system to tolerate f malicious nodes requires at least 3f + 1 nodes. The other problem is the security loopholes of its classical cryptography methods. Here, we propose a quantum Byzantine agreement that exploits the recursion method and quantum digital signatures to break this bound with nearly 1/2 fault-tolerance and provides unconditional security. The consistency check between each pair of rounds ensures the unforgeability and nonrepudiation throughout the whole process. Our protocol is highly practical for its ability to transmit arbitrarily long messages and mature techniques. For the first time, we experimentally demonstrate three-party and five-party quantum consensus for a digital ledger. Our work suggests an important avenue for quantum blockchain and quantum consensus networks.

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Breaking the Rate-Loss Bound of Quantum Key Distribution with Asynchronous Two-Photon Interference

Cited by 162 publications

References 91 publications

Mode-pairing quantum key distribution

Mode-pairing quantum key distribution

Multi-User Measurement-Device-Independent Quantum Key Distribution Based on GHZ Entangled State

Beating the fault-tolerance bound and security loopholes for Byzantine agreement with a quantum solution

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