Continuous Variable Quantum Key Distribution in Multiple-Input Multiple-Output Settings

TL;DR

This paper explores continuous variable quantum key distribution in MIMO optical systems, demonstrating multiplexing gains and robustness against crosstalk and correlated noise, relevant for satellite-based quantum communications.

Contribution

It introduces a $2\times2$ CV QKD model with Gaussian encoding and heterodyne detection, analyzing key rates and showing multiplexing advantages even with channel crosstalk.

Findings

Multiplexing gain achievable with multiple transmitters and receivers.

Performance can surpass multiplexing gain with correlated excess noise.

Analysis applicable to satellite-based quantum communication scenarios.

Abstract

We investigate quantum key distribution (QKD) in optical multiple-input-multiple-output (MIMO) settings. Such settings can prove useful in dealing with harsh channel conditions as in, e.g., satellite-based QKD. We study a $2\times2$ setting for continuous variable (CV) QKD with Gaussian encoding and heterodyne detection and reverse reconciliation. We present our key rate analysis for this system and compare it with single-mode and multiplexed CV QKD scenarios. We show that we can achieve multiplexing gain using multiple transmitters and receivers even if there is some crosstalk between the two channels. In certain cases, when there is nonzero correlated excess noise in the two received signals, we can even surpass the multiplexing gain.