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International Conference on Quantum Communications, Networking, and Computing (QCNC)

Cross Talk in Multiplexed Continuous-Variable Quantum Key Distribution

Olena Kovalenko, Vladyslav C. Usenko

Published Apr 6, 2026• 0 citations
Publisher

Abstract

We address the role of linear inter-mode cross talk in continuous-variable quantum key distribution in the most typical prepare-and-measure scenario. Considering coherent and well as squeezed signal states and either homodyne or heterodyne detection in the receiver station, we show how the cross talk deteriorates the secret key rate and robustness of the protocols to the channel noise. We show how optimization of the signal modulation can improve the performance of the protocols in the presence of cross talk and point out possibilities for further cross talk compensation.

DOI
10.1109/qcnc69040.2026.00100

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Continuous-variable (CV) quantum key distribution (QKD) in optical multiple-antenna settings can be useful in harsh channel conditions despite the presence of cross-talk between channels. This is, for instance, relevant to satellite-based QKD with multiple transmitting antennas on the satellite and multiple ground stations. In such a case, each transmitter independently exchanges data with its intended receiver, where the received signal may contain components from other transmitters. In particular, for a 2×2 multiple-input multiple-output (MIMO) setting with Gaussian encoding and heterodyne detection, preliminary key rate analysis has recently been presented and compared with single-mode and multiplexed CV-QKD scenarios. In this work, we study the effect of different MIMO channels on the performance by accounting for the cross-talk parameter in slow fading channels.