Entropy and asymptotics / Theorem
Mutual information data-processing inequality
Theorem statement
For any bipartite quantum state $\rho_{AB}$ and local quantum channels $\mathcal{N}_{A \to A'}$ and $\mathcal{N}_{B \to B'}$, let $\omega_{A'B'} := (\mathcal{N}_{A \to A'} \otimes \mathcal{N}_{B \to B'})(\rho_{AB})$. Then, the mutual information satisfies $I(A; B)_\rho \ge I(A'; B')_\omega$.
Sources
- Principles of Quantum Communication Theory: A Modern Approach
Sumeet Khatri, Mark M. Wilde, 2024
Lean context
- Lean declaration
QIT.mutualInformation_dataProcessing_local_channels_ge
Copy a short prompt with the import, Lean declaration, citations, and public source link.