Random qubit-states and how best to measure them

Barnett, S.M. (2010) Random qubit-states and how best to measure them. Journal of Modern Optics, 57 (3). pp. 232-238. ISSN 1362-3044 (https://doi.org/10.1080/09500340903082655)

[thumbnail of Randstates.pdf]
Preview
PDF. Filename: Randstates.pdf
Preprint

Download (140kB)| Preview

Abstract

We consider the problem of measuring a single qubit, known to have been prepared in either a randomly selected pure state or a randomly selected real pure state. We seek the measurements that provide either the best estimate of the state prepared or maximise the accessible information. Surprisingly, any sensible measurement turns out to be optimal. We discuss the application of these ideas to multiple qubits and higher-dimensional systems.