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arXiv · 2408.17290

Fundamental Limit on the Power of Entanglement Assistance in Quantum Communication

Lasse H. Wolff·Paula Belzig·Matthias Christandl·Bergfinnur Durhuus·Marco Tomamichel
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Abstract

The optimal rate of reliable communication over a quantum channel can be enhanced by pre-shared entanglement. Whereas the enhancement may be unbounded in infinite-dimensional settings even when the input power is constrained, a long-standing conjecture asserts that the ratio between the entanglement-assisted and unassisted classical capacities is bounded in finite-dimensional settings [Bennett et al., IEEE Trans. Inf. Theory 48, 2637 (2002)]. In this work, we prove this conjecture by showing that their ratio is upper bounded by $o(d^2)$, where $d$ is the input dimension of the channel. An application to quantum communication with noisy encoders and decoders is given.

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Lasse H. Wolff, Paula Belzig, Matthias Christandl, Bergfinnur Durhuus, Marco Tomamichel. 2025-01-25. Fundamental Limit on the Power of Entanglement Assistance in Quantum Communication. https://doi.org/10.1103/physrevlett.134.020802

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