An Operational Meaning of Discord in terms of Teleportation Fidelity

TL;DR

This paper establishes an operational interpretation of quantum discord by linking it to teleportation fidelity, revealing thresholds for Bell inequality violation and providing experimentally accessible bounds.

Contribution

It introduces a new operational meaning of geometric discord based on teleportation fidelity and connects discord levels to Bell inequality violations.

Findings

Discord correlates with teleportation fidelity in two-qubit and higher-dimensional states.

A critical discord value indicates Bell inequality violation.

Lower bounds of discord are experimentally measurable.

Abstract

Quantum discord is a prominent measure of quantum correlations, playing an important role in expanding its horizon beyond entanglement. Here we provide an operational meaning of (geometric) discord, which quantifies the amount of non-classical correlation of an arbitrary quantum system in terms of its minimal distance from the set of classical states, in terms of teleportation fidelity for general two qubit and $d \otimes d$ dimensional isotropic and Werner states. A critical value of the discord is found beyond which the two qubit state must violate the Bell inequality. This is illustrated by an open system model of a dissipative two qubit. For the $d \otimes d$ dimensional states the lower bound of discord is shown to be obtainable from an experimentally measurable witness operator.