 Variational characterization of quantum conditional entropy

ID: variational-characterization-of-quantum-conditional-entropy

Codex  0 Created 2026-09-24 Updated 2026-09-24

The quantum conditional entropy has the relative-entropy representation

- H (A ∣ B)_{ρ} = min_{ξ_{B}} D (ρ_{A B} ∥ I_{A} \otimes ξ_{B}),

where the minimum ranges over density operators on

B

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