- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Monitoring coincident clicks in differential-quadrature-phase shift QKD to reveal detector blinding and control attacks
摘要： Side-channel attacks manipulating single-photon detectors (SPDs) have known to be loopholes in realistic quantum key distribution (QKD) systems. Although measurement-device-independent (MDI) QKD schemes have been proposed and studied to avoid those loopholes, they are not easy to implement in practice because they Require some synchronization between signals sent from two distant parties. In this paper, we propose a new countermeasure against a side-channel attack (control blinding and controlling attacks). It utilizes coincident clicks in differential-quadrature-phase shift (DQPS) QKD systems. Our scheme requires no change in the system configuration of the conventional protocol. Unlike MDI-QKD, side-channel attacks can be found without difficulty in practical implementations.
关键词： DQPS-QKD,quantum key distribution,side-channel attack,single-photon detectors,coincident clicks
更新于2025-09-04 15:30:14
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Hacking Alice's box in continuous-variable quantum key distribution
摘要： Security analyses of quantum cryptographic protocols typically rely on certain conditions; one such condition is that the sender (Alice) and receiver (Bob) have isolated devices inaccessible to third parties. If an eavesdropper (Eve) has a side channel in one of the devices, then the key rate may be sensibly reduced. In this paper we consider an attack on a coherent-state protocol, where Eve not only taps the main communication channel but also hacks Alice’s device. This is done by introducing a Trojan horse mode with low mean number of photons ˉn, which is then modulated in a similar way to the signal state. First we show that this strategy can be reduced to an attack without side channels but with higher loss and noise in the main channel. Then we show how the key rate rapidly deteriorates for increasing photons ˉn, being halved at long distances each time ˉn + 1 doubles. Our work suggests that Alice’s device should also be equipped with sensing systems that are able to detect and estimate the total number of incoming and outgoing photons.
关键词： continuous-variable,side channel,Trojan horse attack,quantum key distribution,security
更新于2025-09-04 15:30:14
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Effects of gravity on continuous-variable quantum key distribution
摘要： The domain of quantum technologies has been recently broadened to satellites orbiting the Earth. Long distance communication protocols cannot ignore the presence of the gravitational field and the effects on the quantum states. Here, we provide a general method to investigate how noninertial motion affects the performance of various quantum key distribution protocols for continuous-variable states of localized wave packets. Taking advantage of the equivalence principle, our results can be thought of as due to the gravitational field. We show that the consequences of gravity strongly depend on the configuration and the cryptographic scheme used.
关键词： noninertial motion,equivalence principle,quantum key distribution,continuous-variable states,gravitational field
更新于2025-09-04 15:30:14
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Miniaturized high-frequency sine wave gating InGaAs/InP single-photon detector
摘要： High-frequency gating InGaAs/InP single-photon detectors (SPDs) are widely used for applications requiring single-photon detection in the near-infrared region such as quantum key distribution. Reducing SPD size is highly desired for practical use, which is favorable to the implementation of further system integration. Here we present, to the best of our knowledge, the most compact high-frequency sine wave gating (SWG) InGaAs/InP SPD. We design and fabricate an InGaAs/InP single-photon avalanche diode (SPAD) with optimized semiconductor structure and then encapsulate the SPAD chip and a mini-thermoelectric cooler inside a butter?y package with a size of 12.5 mm × 22 mm × 10 mm. Moreover, we implement a monolithic readout circuit for the SWG SPD in order to replace the quenching electronics that is previously designed with board-level integration. Finally, the components of SPAD, the monolithic readout circuit, and the af?liated circuits are integrated into a single module with a size of 13 cm × 8 cm × 4 cm. Compared with the 1.25 GHz SWG InGaAs/InP SPD module (25 cm × 10 cm × 33 cm) designed in 2012, the volume of our miniaturized SPD is reduced by 95%. After the characterization, the SPD exhibits excellent performance with a photon detection ef?ciency of 30%, a dark count rate of 2.0 kcps, and an afterpulse probability of 8.8% under the conditions of 1.25 GHz gating rate, 100 ns hold-off time, and 243 K. Also, we perform the stability test over one week, and the results show the high reliability of the miniaturized SPD module.
关键词： InGaAs/InP,quantum key distribution,single-photon detector,miniaturization,sine wave gating
更新于2025-09-04 15:30:14
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Measurement-Device-Independent Quantum Key Distribution over asymmetric channel and unstable channel
摘要： We show that a high key rate of Measurement-Device-Independent Quantum Key Distribution (MDIQKD) over asymmetric and unstable quantum channel can be obtained by full optimization and compensation. Employing a gradient optimization method, we make the full optimization taking both the global optimization for the 12 independent parameters and the joint constraints for statistical fluctuations. We present a loss-compensation method by monitoring the channel loss for an unstable channel. The numerical simulation shows that the method can produce high key rate for both the asymmetric channel and the unstable channel. Compared with the existing results of independent constraints, our result here improves the key rate by 1 to tens of times in typical experimental conditions.
关键词： unstable channel,asymmetric channel,Quantum Key Distribution,loss-compensation method,Measurement-Device-Independent,full optimization
更新于2025-09-04 15:30:14
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Twin-field quantum key distribution with large misalignment error
摘要： Based on the novel idea of twin-field quantum key distribution [TF-QKD; Lucamarini et al., Nature (London) 557, 400 (2018)], we present a protocol named the "sending or not sending TF-QKD" protocol, which can tolerate large misalignment error. A revolutionary theoretical breakthrough in quantum communication, TF-QKD changes the channel-loss dependence of the key rate from linear to square root of channel transmittance. However, it demands the challenging technology of long-distance single-photon interference, and also, as stated in the original paper, the security proof was not finalized there due to the possible effects of the later announced phase information. Here we show by a concrete eavesdropping scheme that the later phase announcement does have important effects and the traditional formulas of the decoy-state method do not apply to the original protocol. We then present our "sending or not sending" protocol. Our protocol does not take postselection for the bits in Z-basis (signal pulses), and hence the traditional decoy-state method directly applies and automatically resolves the issue of security proof. Most importantly, our protocol presents a negligibly small error rate in Z-basis because it does not request any single-photon interference in this basis. Thus our protocol greatly improves the tolerable threshold of misalignment error in single-photon interference from the original a few percent to more than 45%. As shown numerically, our protocol exceeds a secure distance of 700, 600, 500, or 300 km even though the single-photon interference misalignment error rate is as large as 15%, 25%, 35%, or 45%.
关键词： misalignment error,single-photon interference,quantum key distribution,twin-field,decoy-state method
更新于2025-09-04 15:30:14