Distinguishability of generic quantum states

Author Puchała Z.; Pawela Ł.; Życzkowski K.
Title Distinguishability of generic quantum states
Journal Physical Review A
Year 2016
Status Published
Volume 93
Issue 06
DOI 10.1103/PhysRevA.93.062112
URL https://doi.org/10.1103/PhysRevA.93.062112
Abstract <p>Properties of random mixed states of order N distributed uniformly with respect to the Hilbert-Schmidt measure are investigated. We show that for large N, due to the concentration of measure, the trace distance between two random states tends to a fixed number D&nbsp;=1/4+1/π, which yields the Helstrom bound on their distinguishability. To arrive at this result we apply free random calculus and derive the symmetrized Marchenko–Pastur distribution, which is shown to describe numerical data for the model of two coupled quantum kicked tops. Asymptotic values for the fidelity, Bures and transmission distances between two random states are obtained. Analogous results for quantum relative entropy and Chernoff quantity provide other bounds on the distinguishablity of both states in a multiple measurement setup due to the quantum Sanov theorem.</p>