Quantum Conditional Mutual Information, Reconstructed States, and State Redistribution
Brandão, Fernando GSL
Harrow, Aram W
Physical Review Letters
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Brandão, F. G., Harrow, A. W., Oppenheim, J., & Strelchuk, S. (2015). Quantum Conditional Mutual Information, Reconstructed States, and State Redistribution. Physical Review Letters, 115 (050501)https://doi.org/10.1103/PhysRevLett.115.050501
We give two strengthenings of an inequality for the quantum conditional mutual information of a tripartite quantum state recently proved by Fawzi and Renner, connecting it with the ability to reconstruct the state from its bipartite reductions. Namely, we show that the conditional mutual information is an upper bound on the regularized relative entropy distance between the quantum state and its reconstructed version. It is also an upper bound for the measured relative entropy distance of the state to its reconstructed version. The main ingredient of the proof is the fact that the conditional mutual information is the optimal quantum communication rate in the task of state redistribution.
FGSLB and JO thank EPSRC for financial support. AWH was funded by NSF Grants No. CCF- 1111382 and CCF-1452616, ARO Contract No. W911NF-12-1-0486 and a grant from the Leverhulme Trust. S.S. acknowledges the support of Sidney Sussex College.
External DOI: https://doi.org/10.1103/PhysRevLett.115.050501
This record's URL: https://www.repository.cam.ac.uk/handle/1810/249301
Attribution-NonCommercial 2.0 UK: England & Wales
Licence URL: http://creativecommons.org/licenses/by-nc/2.0/uk/
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