2003/01/24 by Sumiyoshi Abe · 2 citations
Physics and Astronomy · #quant-ph #cond-mat.stat-mech
paper · pdf · doi:10.1103/physreva.68.032302
11 pages, no figures
arxiv created 2003/01/24 · arxiv updated 2009/11/30
The Kullback-Leibler divergence offers an information-theoretic basis for measuring the difference between two given distributions. Its quantum analog, however, fails to play a corresponding role for comparing two density matrices, if the reference states are pure states. Here, it is shown that nonadditive (nonextensive) generalization of quantum information theory is free from such a difficulty and the associated quantity, termed the quantum q-divergence, can in fact be a good information-theoretic measure of the degree of purification. The correspondence relation between the ordinary divergence and the q-divergence is violated for the pure reference states, in general.