Leggett-Garg tests of macro-realism for multi-particle systems including double-well Bose-Einstein condensates

TL;DR

This paper develops generalized Leggett-Garg tests for macro-realism applicable to complex quantum systems like Bose-Einstein condensates, demonstrating quantum violations of macro-realism assumptions with various measurement techniques.

Contribution

It introduces new Leggett-Garg inequalities suited for systems where outcomes are not strictly macro-distinguishable, extending tests to entangled and interferometric quantum systems.

Findings

Quantum mechanics predicts violations of the generalized LG inequalities.

Ideal-negative-result, weak, and QND measurements can demonstrate macro-realism negation.

Applicable to Bose-Einstein condensates and atom interferometers.

Abstract

We construct quantifiable generalisations of Leggett-Garg tests for macro/ mesoscopic realism and noninvasive measurability that apply when not all outcomes of measurement can be identified as arising from one of two macroscopically distinguishable states. We show how quantum mechanics predicts a negation of the LG premises for proposals involving ideal-negative-result, weak and quantum non-demolition measurements on dynamical entangled systems, as might be realised with two-well Bose-Einstein condensates, path-entangled NOON states and atom interferometers.