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arXiv · 1901.03476

Information flow versus divisibility for qubit evolution

Sagnik Chakraborty·Dariusz Chruściński
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Abstract

We study the relation between lack of Information Backflow and completely positive divisibility (CP divisibility) for non-invertible qubit dynamical maps. Recently, these two concepts were shown to be fully equivalent for the so called image non-increasing dynamical maps. Here we show that this equivalence is universal for any qubit dynamical map. A key ingredient in our proof is the observation that there does not exist CPTP projector onto a 3-dimensional subspace spanned by qubit density operators. Our analysis is illustrated by several examples of qubit evolution including also dynamical maps which are not image non-increasing.

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Sagnik Chakraborty, Dariusz Chruściński. 2019-01-11. Information flow versus divisibility for qubit evolution. https://doi.org/10.1103/physreva.99.042105

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