Programmed discrimination of qbits with added classical information
Department of Physics, Scottish Universities Physics
Alliance, Strathclyde University, John Anderson Building, 107 Rottenrow, Glasgow
Received in final form: 14 March 2011
Published online: 17 June 2011
We investigate some properties of programmed quantum-state discriminators with simple programs. Bergou et al. [Phys. Rev. A 73, 062334 (2006)] have considered programmable devices which are supplied with two distinct but unknown program qbits and one data qbit which is certain to be identical to one or other of the program qbits. The task is to discriminate between the first and the second possibility. In this paper, we consider this state-discrimination problem when there is some additional classical information available. We find that in the minimum error discrimination mode, the probability of correct discrimination is increased by each type of classical information. The same is broadly true of unambiguous discrimination, with the chance of success improving when the overlap between the program qbits is reduced.
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag 2011