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arXiv:quant-ph/9705036 · Lecture notes in computer science

Data processing in quantum information theory

ARMEN E. ALLAHVERDYAN, David B. Saakian

Published May 21, 1997• 0 citations
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Abstract

The strengthened data processing inequality have been proved. The general theory have been illustrated on the simple example.
DOI
10.48550/arxiv.quant-ph/9705036

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Contraction coefficients give a quantitative strengthening of the data processing inequality. As such, they have many natural applications whenever closer analysis of information processing is required. However, it is often challenging to calculate these coefficients. As a remedy we discuss a quantum generalization of Doeblin coefficients. These give an efficiently computable upper bound on many contraction coefficients. We prove several properties and discuss generalizations and applications. In particular, we give additional stronger bounds. One especially for PPT channels and one for general channels based on a constraint relaxation. Additionally, we introduce reverse Doeblin coefficients that bound certain expansion coefficients.
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