P. W. Lamberti, M. Portesi, J. Sparacino
Published 2008-07-03, updated 2009-04-06Version 2
We study in detail a very natural metric for quantum states. This new proposal has two basic ingredients: entropy and purification. The metric for two mixed states is defined as the square root of the entropy of the average of representative purifications of those states. Some basic properties are analyzed and its relation with other distances is investigated. As an illustrative application, the proposed metric is evaluated for 1-qubit mixed states.
Comments: v2: enlarged; presented at ISIT 2008 (Toronto)
Journal: International Journal of Quantum Information 7 (2009) 1009-1019
Local Invariants for a Class of Mixed States
Unambiguous State Discrimination of two density matrices in Quantum Information Theory
Nonadditive measure and quantum entanglement in a class of mixed states of N^n-system
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