Annihilating and creating nonlocality without entanglement by postmeasurement information

TL;DR

This paper investigates how postmeasurement information can influence nonlocality without entanglement (NLWE) in quantum state discrimination, demonstrating both its annihilation and creation effects in specific two-qubit state ensembles.

Contribution

It reveals that postmeasurement information can control NLWE in separable states, offering new methods to share or hide information using nonorthogonal states.

Findings

Postmeasurement info can annihilate NLWE in certain ensembles.

Postmeasurement info can create NLWE in other ensembles.

Demonstrates control of nonlocality phenomena via measurement information.

Abstract

Nonlocality without entanglement (NLWE) is a nonlocal quantum phenomenon that arises in separable state discrimination. We show that the availability of the postmeasurement information about the prepared subensemble can affect the occurrence of NLWE in discriminating nonorthogonal nonentangled states. We provide a two-qubit state ensemble consisting of four nonorthogonal separable pure states and show that the postmeasurement information about the prepared subensemble can annihilate NLWE. We also provide another two-qubit state ensemble consisting of four nonorthogonal separable states and show that the postmeasurement information can create NLWE. Our result can provide a useful method to share or hide information using nonorthogonal separable states.