Entanglement-Assisted Discrimination of Nonlocal Sets of Orthogonal States

TL;DR

This paper develops resource-efficient protocols for discriminating nonlocal orthogonal quantum states using multipartite entanglement and LOCC, highlighting the operational role of entanglement in quantum information processing.

Contribution

It introduces new LOCC discrimination protocols utilizing multipartite entanglement, reducing resource consumption for nonlocal state discrimination tasks.

Findings

Protocols for GHZ bases in 4- and 5-qubit systems requiring only one EPR pair.

Protocols avoiding teleportation consume fewer resources on average.

Higher-partite GHZ resources can reduce overall entanglement costs.

Abstract

Entanglement-assisted discrimination of orthogonal quantum states exhibiting quantum nonlocality is a frontier topic in quantum information theory. In this paper, we investigate the role of multipartite entanglement and develop resource-efficient LOCC discrimination protocols for nonlocal sets of orthogonal states, including multipartite orthogonal product-state sets and entangled-state sets with different nonlocal features. By incorporating controlled-NOT (CNOT) operations into the discrimination procedure, we construct protocols for genuinely nonlocal GHZ bases in four- and five-qubit systems that require only a single EPR pair. For the same target sets, we compare different entanglement-assisted schemes and identify those with lower entanglement consumption. We further observe that, on average, protocols avoiding teleportation consume fewer resources than teleportation-based approaches. In addition, when higher-partite GHZ-type resources (with $n>3$) are available among suitable subsystems, they can in some cases reduce the overall entanglement cost. Our results highlight the operational significance of multipartite entanglement and provide practical protocols for the local discrimination of orthogonal state sets exhibiting quantum nonlocality.