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Paper 1

Parallel repetition with a threshold in quantum interactive proofs

Abel Molina

Year
2020
Journal
arXiv preprint
DOI
arXiv:2008.07445
arXiv
2008.07445

In this note, we show that $O(\log (1/ε))$ rounds of parallel repetition with a threshold suffice to reduce completeness and soundness error to $ε$ for single-prover quantum interactive proof systems. This improves on a previous $O(\log (1/ε) \log \log (1/ε))$ bound from Hornby (2018), while also simplifying its proof. A key element in our proof is a concentration bound from Impagliazzo and Kabanets (2010).

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Paper 2

Provably Secure and Practical Quantum Key Distribution over 307 km of Optical Fibre

Boris Korzh, Charles Ci Wen Lim, Raphael Houlmann, Nicolas Gisin, Ming Jun Li, Daniel Nolan, Bruno Sanguinetti, Rob Thew, Hugo Zbinden

Year
2014
Journal
arXiv preprint
DOI
arXiv:1407.7427
arXiv
1407.7427

Proposed in 1984, quantum key distribution (QKD) allows two users to exchange provably secure keys via a potentially insecure quantum channel. Since then, QKD has attracted much attention and significant progress has been made in both theory and practice. On the application front, however, the operating distance of practical fibre-based QKD systems is limited to about 150 km, which is mainly due to the high background noise produced by commonly used semiconductor single-photon detectors (SPDs) and the stringent demand on the minimum classical- post-processing (CPP) block size. Here, we present a compact and autonomous QKD system that is capable of distributing provably-secure cryptographic key over 307 km of ultra-low-loss optical fibre (51.9 dB loss). The system is based on a recently developed standard semiconductor (inGaAs) SPDs with record low background noise and a novel efficient finite-key security analysis for QKD. This demonstrates the feasibility of practical long-distance QKD based on standard fibre optic telecom components.

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