Security of hybrid BB84 with heterodyne detection

Fuente: arXiv
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Hauptverfasser: Sidhu, Jasminder S., Maggi, Rocco, Pascazio, Saverio, Lupo, Cosmo
Format: Preprint
Veröffentlicht: 2024
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author Sidhu, Jasminder S.
Maggi, Rocco
Pascazio, Saverio
Lupo, Cosmo
author_facet Sidhu, Jasminder S.
Maggi, Rocco
Pascazio, Saverio
Lupo, Cosmo
contents Quantum key distribution (QKD) promises everlasting security based on the laws of physics. Most common protocols are grouped into two distinct categories based on the degrees of freedom used to carry information, which can be either discrete or continuous, each presenting unique advantages in either performance, feasibility for near-term implementation, and compatibility with existing telecommunications architectures. Recently, hybrid QKD protocols have been introduced to leverage advantages from both categories. In this work we provide a rigorous security proof for a protocol introduced by Qi in 2021, where information is encoded in discrete variables as in the widespread Bennett Brassard 1984 (BB84) protocol but decoded continuously via heterodyne detection. Security proofs for hybrid protocols inherit the same challenges associated with continuous-variable protocols due to unbounded dimensions. Here we successfully address these challenges by exploiting symmetry. Our approach enables truncation of the Hilbert space with precise control of the approximation errors and lead to a tight, semi-analytical expression for the asymptotic key rate under collective attacks. As concrete examples, we apply our theory to compute the key rates under passive attacks, linear loss, and Gaussian noise.
format Preprint
id arxiv_https___arxiv_org_abs_2402_16941
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Security of hybrid BB84 with heterodyne detection
Sidhu, Jasminder S.
Maggi, Rocco
Pascazio, Saverio
Lupo, Cosmo
Quantum Physics
Quantum key distribution (QKD) promises everlasting security based on the laws of physics. Most common protocols are grouped into two distinct categories based on the degrees of freedom used to carry information, which can be either discrete or continuous, each presenting unique advantages in either performance, feasibility for near-term implementation, and compatibility with existing telecommunications architectures. Recently, hybrid QKD protocols have been introduced to leverage advantages from both categories. In this work we provide a rigorous security proof for a protocol introduced by Qi in 2021, where information is encoded in discrete variables as in the widespread Bennett Brassard 1984 (BB84) protocol but decoded continuously via heterodyne detection. Security proofs for hybrid protocols inherit the same challenges associated with continuous-variable protocols due to unbounded dimensions. Here we successfully address these challenges by exploiting symmetry. Our approach enables truncation of the Hilbert space with precise control of the approximation errors and lead to a tight, semi-analytical expression for the asymptotic key rate under collective attacks. As concrete examples, we apply our theory to compute the key rates under passive attacks, linear loss, and Gaussian noise.
title Security of hybrid BB84 with heterodyne detection
topic Quantum Physics
url https://arxiv.org/abs/2402.16941