Abstract
Twin-Field (TF) quantum key distribution (QKD) is a major candidate to be the new benchmark for far-distance QKD implementations, since its secret key rate can overcome the repeaterless bound by means of a simple interferometric measurement. Many variants of the original protocol have been recently proven to be secure. Here, we focus on the TF-QKD type protocol proposed by Curty et al (2019 NPJ Quantum Inf. 5 64), which can provide a high secret key rate and whose practical feasibility has been demonstrated in various recent experiments. The security of this protocol relies on the estimation of certain detection probabilities (yields) through the decoy-state technique. Analytical bounds on the relevant yields have been recently derived assuming that both parties use the same set of decoy intensities, thus providing sub-optimal key rates in asymmetric-loss scenarios. Here we derive new analytical bounds when the parties use either two, three or four independent decoy intensity settings each. With the new bounds we optimize the protocol’s performance in asymmetric-loss scenarios and show that the protocol is robust against uncorrelated intensity fluctuations affecting the parties’ lasers.
Highlights
Quantum Key Distribution (QKD) [1,2,3,4,5] allows two separated parties to generate identical bit strings with information-theoretic security
In this paper we have investigated the performance of the twin-field QKD (TF-QKD) protocol proposed in [19] under the realistic condition of asymmetric losses in the quantum channels linking Alice and Bob to the intermediate node
In contrast to previous results [28], the bounds derived here are valid in the general scenario of independent intensity settings for the two parties, optimizing the protocol’s performance in the presence of asymmetric losses in the two quantum channels
Summary
We focus on the TF-QKD type protocol proposed by Curty et al author(s) and the title of the work, journal citation (2019 NPJ Quantum Inf. 5 64), which can provide a high secret key rate and whose practical feasibility and DOI. Has been demonstrated in various recent experiments The security of this protocol relies on the estimation of certain detection probabilities (yields) through the decoy-state technique. Analytical bounds on the relevant yields have been recently derived assuming that both parties use the same set of decoy intensities, providing sub-optimal key rates in asymmetric-loss scenarios. We derive new analytical bounds when the parties use either two, three or four independent decoy intensity settings each. With the new bounds we optimize the protocol’s performance in asymmetric-loss scenarios and show that the protocol is robust against uncorrelated intensity fluctuations affecting the parties’ lasers
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