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arXiv · quant-ph/0312221

Structure of sufficient quantum coarse-grainings

Milan Mosonyi·Denes Petz
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Abstract

Let H and K be Hilbert spaces and T be a coarse-graining from B(H) to B(K). Assume that density matrices D_1 and D_2 acting on H are given. In the paper the consequences of the existence of a coarse-graining S from B(K) to B(H) satisfying ST(D_1)=D_1 and ST(D_2)=D_2 are given. (This condition means the sufficiency of T for D_1 and D_2.) Sufficiency implies a particular decomposition of the density matrices. This decomposition allows to deduce the exact condition for equality in the strong subadditivity of the von Neumann entropy.

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Milan Mosonyi, Denes Petz. 2003-12-30. Structure of sufficient quantum coarse-grainings. https://doi.org/10.1007/s11005-004-4072-2

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