Continuous QKD and high speed data encryption

Zbinden, Hugo; Walenta, Nino; Guinnard, Olivier; Houlmann, Raphaël; Lim, Charles Ci Wen; Korzh, Boris; Lunghi, Tommaso; Gisin, Nicolas; Burg, Andreas; Constantin, Joseph; Legré, M; Trinkler, Patrick; Caselunghe, Dario; Kulesza, Natalia; Trolliet, Gregory; Vannel, Fabien; Junod, Pascal; Auberson, Olivier; Graf, Yoan; Curchod, Gilles; Habegger, Gilles; Messerli, Etienne; Portmann, Christopher; Henzen, Luca; Keller, Christoph A.; Pendl, Christian; Mühlberghuber, Michael; Roth, Christoph; Felber, N.; Gürkaynak, Frank K.; Schöni, Daniel; Muheim, Beat

doi:10.1117/12.2032731

Cited by 1 publication

(1 citation statement)

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“…While QKD has been well-studied over the past 30 years, the exploration of long-distance CV-QKD is still nascent, with very few published implementations in the low-SNR regime for optical transmission distances beyond 100km. Hardwarebased implementations of DV-QKD and short-distance CV-QKD have previously been demonstrated using FPGAs and GPUs [26], [27], [74], [88], however, at the time of writing, there is only one reported CV-QKD implementation designed to operate in the low-SNR regime for long-distance reconciliation [25]. GPU Memory Bandwidth (GB/s) 320 264 (1) FER P e corresponds to the probability of detected error, since P undetected = 0 with 32-bit CRC.…”

Section: Comparison To Other Cv-qkd Implementationsmentioning

confidence: 99%

Key Reconciliation with Low-Density Parity-Check Codes for Long-Distance Quantum Cryptography

Milicevic,

Feng,

Zhang

et al. 2017

Preprint

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The speed at which two remote parties can exchange secret keys over a fixed-length fiber-optic cable in continuousvariable quantum key distribution (CV-QKD) is currently limited by the computational complexity of post-processing algorithms for key reconciliation. Multi-edge low-density paritycheck (LDPC) codes with low code rates and long block lengths were proposed for CV-QKD, in order to extend the maximum reconciliation distance between the two remote parties. Key reconciliation over multiple dimensions has been shown to further improve the error-correction performance of multi-edge LDPC codes in CV-QKD, thereby increasing both the secret key rate and distance. However, the computational complexity of LDPC decoding for long block lengths on the order of 10 6 bits remains a challenge. This work introduces a quasi-cyclic (QC) code construction for multi-edge LDPC codes that is highly suitable for hardware-accelerated decoding on a modern graphics processing unit (GPU). When combined with an 8-dimensional reconciliation scheme, the LDPC decoder achieves a raw decoding throughput of 1.72Mbit/s and an information throughput of 7.16Kbit/s using an NVIDIA GeForce GTX 1080 GPU at a maximum distance of 160km with a secret key rate of 4.10×10 −7 bits/pulse for a rate 0.02 multi-edge code with block length of 10 6 bits when finite-size effects are considered. This work extends the previous maximum CV-QKD distance of 100km to 160km, while delivering between 1.07× and 8.03× higher decoded information throughput over the upper bound on the secret key rate for a lossy channel. For distances beyond 130km, the GPU decoder delivers an information throughput between 1868× and 18790× higher than the achievable secret key rates with a 1MHz light source. The GPU-based QC-LDPC decoder achieves a 1.29× improvement in throughput over the best existing GPU decoder implementation for a rate 1/10 multi-edge LDPC code with block length of 2 20 bits. These results show that LDPC decoding is no longer the computational bottleneck in long-distance CV-QKD, and that the secret key rate remains limited only by the physical parameters of the quantum channel and the latency of privacy amplification.

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