Postselection technique for optical Quantum Key Distribution with improved de Finetti reductions

Fuente: arXiv
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Autori principali: Nahar, Shlok, Tupkary, Devashish, Zhao, Yuming, Lütkenhaus, Norbert, Tan, Ernest Y. -Z.
Natura: Preprint
Pubblicazione: 2024
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author Nahar, Shlok
Tupkary, Devashish
Zhao, Yuming
Lütkenhaus, Norbert
Tan, Ernest Y. -Z.
author_facet Nahar, Shlok
Tupkary, Devashish
Zhao, Yuming
Lütkenhaus, Norbert
Tan, Ernest Y. -Z.
contents The postselection technique is an important proof technique for proving the security of quantum key distribution protocols against coherent attacks. In this work, we go through multiple steps to rigorously apply the postselection technique to optical quantum key distribution protocols. First, we place the postselection technique on a rigorous mathematical foundation by fixing a technical flaw in the original postselection paper. Second, we extend the applicability of the postselection technique to prepare-and-measure protocols by using a de Finetti reduction with a fixed marginal. Third, we show how the postselection technique can be used for decoy-state protocols by tagging the source. Finally, we extend the applicability of the postselection technique to realistic optical setups by developing a new variant of the flag-state squasher. We also improve existing de Finetti reductions, which reduce the effect of using the postselection technique on the key rate. These improvements can be more generally applied to other quantum information processing tasks. As an example to demonstrate the applicability of our work, we apply our results to the time-bin encoded three-state protocol. We observe that the postselection technique performs better than all other known proof techniques against coherent attacks.
format Preprint
id arxiv_https___arxiv_org_abs_2403_11851
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Postselection technique for optical Quantum Key Distribution with improved de Finetti reductions
Nahar, Shlok
Tupkary, Devashish
Zhao, Yuming
Lütkenhaus, Norbert
Tan, Ernest Y. -Z.
Quantum Physics
Mathematical Physics
Optics
The postselection technique is an important proof technique for proving the security of quantum key distribution protocols against coherent attacks. In this work, we go through multiple steps to rigorously apply the postselection technique to optical quantum key distribution protocols. First, we place the postselection technique on a rigorous mathematical foundation by fixing a technical flaw in the original postselection paper. Second, we extend the applicability of the postselection technique to prepare-and-measure protocols by using a de Finetti reduction with a fixed marginal. Third, we show how the postselection technique can be used for decoy-state protocols by tagging the source. Finally, we extend the applicability of the postselection technique to realistic optical setups by developing a new variant of the flag-state squasher. We also improve existing de Finetti reductions, which reduce the effect of using the postselection technique on the key rate. These improvements can be more generally applied to other quantum information processing tasks. As an example to demonstrate the applicability of our work, we apply our results to the time-bin encoded three-state protocol. We observe that the postselection technique performs better than all other known proof techniques against coherent attacks.
title Postselection technique for optical Quantum Key Distribution with improved de Finetti reductions
topic Quantum Physics
Mathematical Physics
Optics
url https://arxiv.org/abs/2403.11851