Strong Converse Exponent of Quantum State Merging

Abstract:We determine the strong converse exponent for the entanglement cost of quantum state merging, showing that it is characterized by the optimized $\alpha$-$z$ conditional Rényi entropies with $z=\alpha/2\in[1/2,1]$. This contrasts with the sandwiched conditional Rényi entropies that typically govern strong converse exponents in quantum information theory. As a consequence, we derive the strong converse exponent of the partially smoothed conditional min-entropy in purified distance. This exponent is governed by club-sandwiched conditional entropies, whereas global smoothing leads to a sandwiched expression.

Quantum Physics (quant-ph); Information Theory (cs.IT)

arXiv:2608.27202 [quant-ph]

(or arXiv:2608.27202v1 [quant-ph] for this version)

https://doi.org/10.48550/arXiv.2608.27202 Focus to learn more arXiv-issued DOI via DataCite (pending registration)

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