Robust and efficient quantum key distribution with practical devices

Anonymous, Wei-Xin Xie, Chun-Mei Zhang +9 more

Measurement-device-independent quantum key distribution (MDI-QKD) is a promising path toward practical quantum communication, but current high-performance demonstrations come at prohibitive overhead and isolated environments. Here, we present a high-speed MDI-QKD system operating at an unprecedented repetition frequency of 2.5 GHz and verify its strong noise tolerance by incorporating the advantage distillation method. The secure key is efficiently generated under 425 kHz noise counts, which is 4 orders of magnitude higher than isolated systems. A secure key rate with a kbps level is achieved under 30 dB channel attenuation without bulky, resource-intensive detection devices. Our Letter establishes a complete practical solution for QKD deployment and resolves the persistent difficulty of realizing practical quantum secure networks with advanced security, a high key rate, environmental robustness, and physical compactness.

Tapster, Gorman, Benton +3 more

Masato Koashi

We consider the security of a system of quantum key distribution (QKD) using only practical devices. Currently, attenuated laser pulses are widely used and considered to be the most practical light source. For the receiver of photons, threshold (or on/off) photon detectors are almost the only choice. Combining the decoy-state idea and the security argument based on the uncertainty principle, we show that a QKD system composed of such practical devices can achieve the unconditional security without any significant penalty in the key rate and the distance limitation.

Esther Hänggi, Renato Renner, Stefan Wolf

Monika Mothsara, Suraj Goel, Bohnishikha Ghosh +4 more

Quantum key distribution (QKD) brings the promise of communication with information-theoretic security but is limited in practice due to its susceptibility to noise, losses, and device imperfections. To address these challenges, we propose a robust high-dimensional (HD) one-sided device-independent QKD (1sDI-QKD) protocol and present a proof-of-principle experimental implementation using photons entangled in the transverse-spatial degree-of-freedom. We develop a systematic security analysis of HD 1sDI-QKD protocols, leveraging quantum steering to certify security, and evaluate achievable secret key rates for different measurement configurations and system dimensions using reverse reconciliation. Our analysis shows that increasing the dimension enhances robustness against both noise and loss. We then demonstrate the key experimental building blocks required for implementing the protocol: (a) a high-quality source of high-dimensional photonic entanglement, and (b) a fully programmable, high-dimensional multi-outcome measurement device operating in up to dimension 11. Using these components, we obtain positive key rates for all investigated dimensions under the fair-sampling assumption, with the highest key rates achieved for dimension d=7. Finally, we discuss the steps required for a practical, loophole-free implementation of 1sDI-QKD in realistic regimes of loss and noise.

Norbert Lütkenhaus