12 Quantum States: Discrimination and Classical Information Transmission.A Review of Experimental Progress

Abstract

The purpose of this chapter is to review the experimental achievements made to date in two closely related areas of quantum information science. These are quantum state discrimination and classical information transmission using quantum states. In all experiments, the states were realised as quantum states of light. We begin by describing experimental implementations of two optimum discrimination strategies for a pair of nonorthogonal states. These are minimum error state discrimination and optimum unambiguous state discrimination. We then consider minimum error discrimination among certain, highly symmetrical sets of three and four states. The measurements involved were closely related to those required to attain the accessible information for such states. These measurements were also implemented. Subsequent accessible information experiments for up to seven quantum states are then described. The final experiment we discuss is an implementation of a novel, non-classical effect in quantum communications known as classical capacity superadditivity.