- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Polarization attack on continuous-variable quantum key distribution
摘要： The shot-noise unit (SNU) is a crucial factor for the practical security of a continuous-variable quantum key distribution system. In the most widely used experimental scheme, the SNU should be calibrated first and acts as a constant during the key distribution. However, the SNU of a practical system is dependent on the various parameters of the local oscillator (LO), which can be controlled by the eavesdropper in the open channel. In this paper, we report a quantum hacking method to control the practical SNU by using the limited compensation rate of the polarization compensation. Since the compensation is only based on of the polarization measurement results of part of LO pulses, the polarization of other unmeasured pulses may not be compensated correctly, which can be utilized by the eavesdropper to control the practical SNU. The simulation and experiment results indicate that the practical SNU can be controlled by the eavesdropper. Thus, the eavesdropper can use the fact that the practical SNU is no longer equals to the calibrated one to control the excess noise and final key rate.
关键词： shot noise unit,polarization compensation,continuous-variable quantum key distribution,quantum hacking
更新于2025-09-23 15:23:52
-
Parameter optimization of cascade in quantum key distribution
摘要： Quantum key distribution (QKD) protocol mainly includes two stages: signal transmission stage based on quantum channel and post-processing stage based on classical channel, and the post-processing stage has gradually become a bottleneck restricting the high performance of QKD. Information reconciliation (IR) is a key step in post-processing. Cascade has been widely used in IR due to its excellent error correction performance. In this study, we analyze original Cascade and adjust parameters to improve the partition strategy. As a result, more errors are corrected under near-optimal conditions. We consider both reconciliation efficiency and frame error rate to measure protocol performance. Simulation shows that the improved Cascade can effectively improve the reconciliation efficiency while ensuring a small frame error rate. Overall, our improved Cascade has better performance on the final secret key rate.
关键词： Information reconciliation,Quantum key distribution,Cascade protocol
更新于2025-09-23 15:23:52
-
Efficient scheme for passive decoy-state reference-frame-independent quantum key distribution
摘要： Reference-frame-independent quantum key distribution (RFI-QKD) has been demonstrated to be reliable and useful both in theories and experiments, which is intrinsically robust against slowly varying reference frames. In this paper, we propose an efficient scheme of passive decoy-state RFI-QKD based on the parametric down-conversion source, where a beam splitter splits the idler pulses into four local detection events to improve the performance of RFI-QKD systems. In addition, we demonstrate the worst relative rotation of reference frames in our scheme. Simulation results show that our scheme can achieve good performance even at the worst-case scenario.
关键词： Quantum key distribution,Passive decoy-state,Reference-frame-independent
更新于2025-09-23 15:23:52
-
Memory-assisted quantum key distribution resilient against multiple-excitation effects
摘要： Memory-assisted measurement-device-independent quantum key distribution (MA-MDI-QKD) has recently been proposed as a technique to improve the rate-versus-distance behavior of QKD systems by using existing, or nearly-achievable, quantum technologies. The promise is that MA-MDI-QKD would require less demanding quantum memories than the ones needed for probabilistic quantum repeaters. Nevertheless, early investigations suggest that, in order to beat the conventional memory-less QKD schemes, the quantum memories used in the MA-MDI-QKD protocols must have high bandwidth-storage products and short interaction times. Among different types of quantum memories, ensemble-based memories offer some of the required specifications, but they typically suffer from multiple excitation effects. To avoid the latter issue, in this paper, we propose two new variants of MA-MDI-QKD both relying on single-photon sources for entangling purposes. One is based on known techniques for entanglement distribution in quantum repeaters. This scheme turns out to offer no advantage even if one uses ideal single-photon sources. By finding the root cause of the problem, we then propose another setup, which can outperform single memory-less setups even if we allow for some imperfections in our single-photon sources. For such a scheme, we compare the key rate for different types of ensemble-based memories and show that certain classes of atomic ensembles can improve the rate-versus-distance behavior.
关键词： quantum cryptography,quantum networks,quantum key distribution (QKD),quantum memory,single-photon source,quantum communications
更新于2025-09-23 15:22:29
-
Polarization-based plug-and-play measurement-device-independent quantum key distribution
摘要： Measurement-device-independent quantum key distribution (MDI-QKD) has received much attention, with the goal of overcoming all of the security loopholes caused by an imperfect detection system. We here propose a plug-and-play MDI-QKD (P&P MDI-QKD) scheme whereby an untrusted relay node, Charlie, owns a laser and sends photons to Alice and Bob. Alice (Bob) modulates the polarization of the incident photons and returns them to Charlie. Charlie uses a modified Bell state analyzer (BSA) to perform Bell state measurements (BSM). In comparison with the original version of MDI-QKD, our scheme exploits a single untrusted laser as the photon source. This makes the signal photons identical and enhances the Hong-Ou-Mandel effect. Second, because of the P&P structure, the setup can automatically eliminate the birefringence influence of the fibers, which makes the setup highly stable. Finally, our modified BSA can identify |Φ?+ and |Φ?? of four Bell states with polarization encoding but not |Ψ?+ and |Ψ??. Based on practical experimental parameters, a simulation showed that the maximum theoretical secure transmission distance could reach more 280 km.
关键词： Plug-and-play,Measurement-device-independent,Quantum cryptography,Quantum key distribution
更新于2025-09-23 15:22:29
-
Resource state structure for controlled quantum key distribution
摘要： Quantum entanglement plays a pivotal role in many communication protocols, like secret sharing and quantum cryptography. We consider a scenario where more than two parties are involved in a protocol and share a multipartite entangled state. In particular, we considered the protocol of Controlled Quantum Key Distribution (CoQKD), introduced in the reference H. Chao, X. Peng, and G. G-Can, Chin. Phys. Lett. 20, 183 (2003), where, two parties, Alice and Bob establish a key with the cooperation of other parties. Other parties control/supervise whether Alice and Bob can establish the key, its security and key rate. We discuss the case of three parties in detail and find suitable resource states. We discuss the controlling power of the third party, Charlie. We also examine the usefulness of the new resource states for generating conference key and for cooperative teleportation. We find that recently introduced Bell inequalities can be useful to establish the security of the conference key. We also generalize the scenario to more than three parties.
关键词： conference key,cooperative teleportation,Bell inequalities,CoQKD,Quantum entanglement,Controlled Quantum Key Distribution
更新于2025-09-23 15:21:01
-
Sending-or-Not-Sending with Independent Lasers: Secure Twin-Field Quantum Key Distribution over 509??km
摘要： Twin-field (TF) quantum key distribution (QKD) promises high key rates over long distances to beat the rate-distance limit. Here, applying the sending-or-not-sending TF QKD protocol, we experimentally demonstrate a secure key distribution that breaks the absolute key-rate limit of repeaterless QKD over a 509-km-long ultralow loss optical fiber. Two independent lasers are used as sources with remote-frequency-locking technique over the 500-km fiber distance. Practical optical fibers are used as the optical path with appropriate noise filtering; and finite-key effects are considered in the key-rate analysis. The secure key rate obtained at 509 km is more than seven times higher than the relative bound of repeaterless QKD for the same detection loss. The achieved secure key rate is also higher than that of a traditional QKD protocol running with a perfect repeaterless QKD device, even for an infinite number of sent pulses. Our result shows that the protocol and technologies applied in this experiment enable TF QKD to achieve a high secure key rate over a long distribution distance, and is therefore practically useful for field implementation of intercity QKD.
关键词： remote-frequency-locking technique,repeaterless QKD,ultralow loss optical fiber,secure key distribution,Twin-field quantum key distribution
更新于2025-09-23 15:19:57
-
Measurement-Device-Independent Entanglement Witness of Tripartite Entangled States and Its Applications
摘要： Entanglement witness is of great importance in characterizing quantum systems. The imperfections in conventional entanglement witness schemes could lead to the misidentification of a separated state as an entangled state. Measurement-device-independent entanglement witness (MDIEW) has been proposed and demonstrated to resolve the imperfect measurement devices. So far, however, the MDIEW has been restricted to a two-party qubit entangled state. Here, for the first time, we demonstrate MDIEW for multipartite entangled states. We experimentally detect the genuine entanglement and the entanglement structure of a tripartite entangled state based on an eight-photon interferometry. Furthermore, with the verified multipartite entangled state, we demonstrate quantum randomness generation and open-destination quantum key distribution in an measurement-device-independent manner. Our research presents an important step toward building a robust and secure quantum network.
关键词： quantum key distribution,quantum randomness generation,multipartite entangled states,entanglement witness
更新于2025-09-23 15:19:57
-
[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Influence of UV light on the increase of SiN <sub/>x</sub> conductivity toward elucidation of potential induced degradation mechanism
摘要： The main type of obstacles of practical applications of quantum key distribution (QKD) network are various attacks on detection. Measurement-device-independent QKD (MDIQKD) protocol is immune to all these attacks, and thus, a strong candidate for network security. Recently, several proof-of-principle demonstrations of MDIQKD have been performed. Although novel, those experiments are implemented in the laboratory with secure key rates less than 0.1 b/s. Besides, they need manual calibration frequently to maintain the system performance. These aspects render these demonstrations far from practicability. Thus, justification is extremely crucial for practical deployment into the field environment. Here, by developing an automatic feedback MDIQKD system operated at a high clock rate, we perform a field test via deployed fiber network of 30 km total length achieving a 16.9 b/s secure key rate. The result lays the foundation for a global quantum network, which can shield from all the detection-side attacks.
关键词： measurement-device-independent quantum key distribution,automatic feedback systems,Field test
更新于2025-09-23 15:19:57
-
Finite-key effects in multipartite quantum key distribution protocols
摘要： We analyze the security of two multipartite quantum key distribution (QKD) protocols, specifically we introduce an N-partite version of the BB84 protocol and we discuss the N-partite six-state protocol proposed by Epping et al (2017 New J. Phys. 19 093012). The security analysis proceeds from the generalization of known results in bipartite QKD to the multipartite scenario, and takes into account finite resources. In this context we derive a computable expression for the achievable key rate of both protocols by employing the best-known strategies: the uncertainty relation and the postselection technique. We compare the performances of the two protocols both for finite resources and infinitely many signals.
关键词： finite resources,conference key agreement,quantum key distribution,uncertainty relation for smooth entropies,finite-key effects,security analysis,multipartite qkd
更新于2025-09-19 17:15:36