Topic
Classical capacity
7 records: 4 unsolved, 3 solved. Filter the catalog by this topic →
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Closed-form nonadditivity of the Holevo capacity and entanglement of formation
Construct a simple closed-form or practically computable counterexample to additivity of the Holevo capacity or the entanglement of formation, together with a rigorous certificate of a strict violation.
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Candidate pure-loss second-order converse
Does the pure-loss bosonic channel admit the following candidate second-order classical converse under a maximum-photon-number occupation constraint?
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Holevo random-coding exponent for classical–quantum channels
Does every memoryless classical–quantum channel with a finite input alphabet and finite-dimensional output satisfy the random-coding lower bound in Eq. (5), including channels with mixed, noncommuting output states?
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Low-energy Holevo additivity for a squeezed thermal attenuator
Is energy-constrained Holevo information additive for a squeezed thermal attenuator below its water-filling threshold?
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Universal strong converse for the classical capacity
Does every finite-dimensional quantum channel satisfy the strong converse property at its unassisted classical capacity, or does some channel admit a sequence of codes above capacity whose average success probability stays bounded away from zero?
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Uniformly efficient HSW pretty-good decoding
Can Holevo–Schumacher–Westmoreland codebooks operating at every rate below their ensemble Holevo information be chosen so that their square-root, or pretty-good, measurements have uniform quantum implementations whose cost is polynomial in the blocklength and…
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Structural criterion for classical–entanglement trade-off advantage
Characterize the finite-dimensional quantum channels for which joint classical–entanglement coding strictly outperforms time sharing between unassisted and unlimited-entanglement classical communication.
Unsolved