Fidelity between random quantum states - Karol ¯yczkowski

We review relevant probability measures in the space of mixed quantum states of a finite size (including Hilbert-Schmidt measure, Bures measure, and measures induced by partial tracing of random pure states of the extended system) and discuss their properties and possible applications. Assuming that two random mixed states are generated according to one of these measures we compute average fidelity between them. Average value obtained may be used to gauge the quality of quantum information processing schemes.