Theoretical Falsification of Leggett Conjecture for Two Qubits or One Ququat

TL;DR

This paper presents a theoretical inequality to falsify the Leggett model for a two-qubit subsystem, extending previous experimental and theoretical efforts to larger systems, and discusses alternative interpretations of the results.

Contribution

It introduces a new inequality that can theoretically reject the Leggett model specifically for a two-qubit subsystem, advancing the understanding of quantum correlations.

Findings

Derived an inequality to falsify the Leggett model for two qubits

Extended previous work on Leggett model testing to smaller subsystems

Discussed alternative interpretations of the derived inequality

Abstract

Recently, some attention has been paid to falsifying the Leggett model, in which global probabilities characterizing a quantum state are represented by a combination of factorisable distributions. This idea was even verified in experiments, and generalized for larger subsystems, but thus far not in terms of the size of a subsystem. In this communication we show an inequality to reject the Leggett description for a subsystem of two qubits. We also point out some other interpretations of the derived expression.