Minimum-error multiple state discrimination constrained by the no-signaling principle

TL;DR

This paper establishes a universal bound on the minimum error in quantum state discrimination based on the no-signaling principle, applicable to various quantum states and strengthening the link between fundamental quantum constraints.

Contribution

It introduces a general, dimension-independent bound on quantum state discrimination error derived from the no-signaling principle, applicable even when optimal strategies are unknown.

Findings

Bound is tight for symmetric qubit states

Applicable to unknown state sets

Strengthens the connection between no-signaling and no perfect state estimation

Abstract

We provide a bound on the minimum error when discriminating among quantum states, using the no-signaling principle. The bound is general in that it depends on neither dimensions nor specific structures of given quantum states to be discriminated among. We show that the bound is tight for the minimum-error state discrimination between symmetric (both pure and mixed) qubit states. Moreover, the bound can be applied to a set of quantum states for which the minimum-error state discrimination is not known yet. Finally, our results strengthen the quantitative connection between two no-go theorems, the no-signaling principle and the no perfect state estimation.