Factorizability of optimal quantum sequence discrimination under maximum-confidence measurements

TL;DR

This paper demonstrates that optimal quantum sequence discrimination under maximum-confidence measurements can be achieved by independently discriminating each sequence element, simplifying the process and providing conditions for optimality.

Contribution

It establishes that sequence discrimination can be factorized into individual discriminations and provides a necessary and sufficient condition for optimality under maximum-confidence measurements.

Findings

Optimal discrimination can be achieved by independent measurements at each step.

Maximum confidence for sequences equals the minimum confidence among individual states.

Provides a necessary and sufficient condition for optimal quantum state discrimination.

Abstract

We consider the discrimination of quantum sequences under maximum-confidence measurements and show that the optimal discrimination of a quantum sequence ensemble can always be factorized into that of each individual ensemble. In other words, the optimal quantum sequence discrimination under maximum-confidence measurements can be achieved just by performing a maximum-confidence discrimination independently at each step of the quantum sequence. We also show that the maximum confidence of identifying a quantum sequence is to achieve the maximum confidence of identifying each state comprising the quantum sequence. We further provide a necessary and sufficient condition for the optimal quantum state discrimination under maximum-confidence measurements.