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A simple proof of the strong subadditivity inequality

Quantum Physics 2007-05-23 v3

Abstract

Arguably the deepest fact known about the von Neumann entropy, the strong subadditivity inequality is a potent hammer in the quantum information theorist's toolkit. This short tutorial describes a simple proof of strong subadditivity due to Petz [Rep. on Math. Phys. 23 (1), 57--65 (1986)]. It assumes only knowledge of elementary linear algebra and quantum mechanics.

Keywords

Cite

@article{arxiv.quant-ph/0408130,
  title  = {A simple proof of the strong subadditivity inequality},
  author = {Michael A. Nielsen and Denes Petz},
  journal= {arXiv preprint arXiv:quant-ph/0408130},
  year   = {2007}
}

Comments

7 pages, resubmitted version of a tutorial paper submitted to Quantum Information and Computation

R2 v1 2026-07-22T19:45:40.160Z