Co-transmission of classical data and continuous-variable entanglement over a single quantum channel

Nicholas Zaunders; Timothy C. Ralph

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arXiv · 2607.25179

Co-transmission of classical data and continuous-variable entanglement over a single quantum channel

Nicholas Zaunders·Timothy C. Ralph

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Abstract

Displacement-based simultaneous quantum-classical communications (SQCC) protocols, as originally proposed, are generally incompatible with the majority of useful quantum communication schemes, such as entanglement distribution or repeater-based quantum key distribution: direct measurement of the classical signal also measures and destroys the quantum state, leaving point-to-point Gaussian quantum key distribution as the only quantum communication scheme amenable to integration with SQCC. In this work, we apply the classically-modulated quantum communication protocol proposed by Zaunders and Ralph [arXiv:2606.03181v3] to circumvent this issue and demonstrate the distribution of continuous-variable Gaussian entanglement simultaneously with classical information. We characterise the quality of the distributed entangled state and outline how the scheme is suitable for use in repeater-based networks. Lastly, we compute the secret key generation rate of the Gaussian CMQC scheme in the point-to-point case and compare it to the equivalent point-to-point SQCC protocol.

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Nicholas Zaunders, Timothy C. Ralph. 2026-08-03. Co-transmission of classical data and continuous-variable entanglement over a single quantum channel. https://arxiv.org/abs/2607.25179

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