Average fidelity between random quantum states

Abstract

We analyze mean fidelity between random density matrices of size N, generated with respect to various probability measures in the space of mixed quantum states: Hilbert-Schmidt measure, Bures (statistical) measure, the measures induced by partial trace and the natural measure on the space of pure states. In certain cases explicit probability distributions for fidelity are derived. Results obtained may be used to gauge the quality of quantum information processing schemes.

15 revtex pages with 4 figures; Ver. 2: another distribution derived, an extra figure included, Ver. 3: comments in introduction and conclusion added ver 4. minor improvments