Elsevier

Theoretical Computer Science

Volume 801, 1 January 2020, Pages 35-63
Theoretical Computer Science

Singular value decomposition assisted multicarrier continuous-variable quantum key distribution

https://doi.org/10.1016/j.tcs.2019.07.029Get rights and content
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Abstract

We define the singular value decomposition (SVD) assisted multicarrier continuous-variable quantum key distribution (CVQKD) protocol. The proposed protocol uses the singular value decomposition of the Gaussian quantum channel, which yields an additional degree of freedom for the phase space transmission. This additional degree of freedom can further be exploited in a multiple-access scenario. The SVD-assistance defines the eigenchannels of the Gaussian physical link, which can be used for the simultaneous reliable transmission of multiple user data streams. Our transmission model also includes the singular interference avoider (SIA) precoding scheme. The proposed SIA precoding scheme prevents the eigenchannel interference to reach an optimal transmission over a Gaussian link. We demonstrate the results through the adaptive multicarrier quadrature division–multiuser quadrature allocation (AMQD-MQA) CVQKD multiple-access scheme. The singular value assisted transmission provides improved simultaneous transmission rates for the users, particularly in crucial low signal-to-noise ratio regimes.

Keywords

Quantum key distribution
Quantum cryptography
Quantum communications
Continuous-variables
Quantum Shannon theory

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Parts of this work were presented in conference proceedings [42], [52].