No-Signalling Bound on Quantum State Discrimination

TL;DR

This paper explores how the no-signalling principle constrains quantum state discrimination, linking maximum confidence strategies to fundamental quantum correlations and entanglement concentration.

Contribution

It derives bounds on quantum state discrimination based on no-signalling, connecting maximum confidence measurements with entanglement concentration.

Findings

Maximum confidence measurements can be derived from no-signalling constraints.

The no-signalling principle imposes fundamental limits on quantum state discrimination.

Maximum confidence strategies relate to entanglement concentration processes.

Abstract

Quantum correlations do not allow signalling, and any operation which may be performed on one system of an entangled pair cannot be detected by measurement of the other system alone. This no-signalling condition limits allowed operations and, in the context of quantum communication, may be used to put bounds on quantum state discrimination. We find that the natural figure of merit to consider is the confidence in identifying a state, which is optimised by the maximum confidence strategy. We show that this strategy may be derived from the no-signalling condition, and demonstrate the relationship between maximum confidence measurements and entanglement concentration.