Continuous-variable quantum key distribution with noisy squeezed states

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61989592%3A15310%2F25%3A73628858" target="_blank" >RIV/61989592:15310/25:73628858 - isvavai.cz</a>

Result on the web

<a href="https://iopscience.iop.org/article/10.1088/2058-9565/ada9c4" target="_blank" >https://iopscience.iop.org/article/10.1088/2058-9565/ada9c4</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1088/2058-9565/ada9c4" target="_blank" >10.1088/2058-9565/ada9c4</a>

Result language

angličtina

Original language name

Continuous-variable quantum key distribution with noisy squeezed states

Original language description

We address the crucial role of noisy squeezing in security and performance of continuous-variable (CV) quantum key distribution (QKD) protocols. Squeezing has long been recognized for its numerous advantages in CV QKD, such as enhanced robustness against channel noise and loss, and improved secret key rates. However, the excess noise of the squeezed states, that unavoidably originates already from optical loss as well as other imperfections in the source, raises concerns about its potential exploitation by an eavesdropper. For the widely adopted trust assumption on the excess noise in the signal states, we confirm the stability of the protocol against the noisy squeezing in both purely attenuating as well as noisy channels in the asymptotic limit, which implies perfect parameter estimation. In the finite-size regime we show that this stability largely holds at up to 107 data points using optimal biased homodyne detection for key distribution and parameter estimation. Untrusted assumption on the noisy squeezing, on the other hand, introduces additional security bounds on the squeezing excess noise already in the asymptotic regime, which is further enforced by the finite-size effects. Additionally, we show the critical negative role of noisy squeezing in the case of atmospheric free-space channels, already in the trusted-noise and asymptotic assumptions, which emphasizes the importance of squeezing purity in the free-space quantum channels. Our results pave the way towards practical realization of squeezed-state CV QKD protocols in both fibre and free-space channels.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

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OECD FORD branch

10306 - Optics (including laser optics and quantum optics)

Project

Result was created during the realization of more than one project. More information in the Projects tab.

Continuities

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)<br>S - Specificky vyzkum na vysokych skolach

Publication year

2025

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Quantum Science and Technology

ISSN

2058-9565

e-ISSN

—

Volume of the periodical

10

Issue of the periodical within the volume

2

Country of publishing house

GB - UNITED KINGDOM

Number of pages

23

Pages from-to

"025023-1"-"025023-23"

UT code for WoS article

001418121900001

EID of the result in the Scopus database

2-s2.0-85218623791