Violation of a Leggett-Garg inequality using ideal negative measurements in neutron interferometry

TL;DR

This paper reports an experiment with neutron interferometry that demonstrates a violation of a Leggett-Garg inequality, providing evidence against macro-realistic theories and supporting quantum mechanics predictions.

Contribution

It presents the first neutron interferometry test of LGI violation using ideal negative measurements, advancing experimental tests of quantum realism.

Findings

Measured K = 1.120 ± 0.007 exceeds the macro-realistic limit of 1.

Confirms quantum mechanics predictions over macro-realistic theories.

Demonstrates feasibility of LGI tests with neutrons in interferometry.

Abstract

We report on an experiment that demonstrates the violation of a Leggett-Garg inequality (LGI) with neutrons. LGIs have been proposed in order to assess how far the predictions of quantum mechanics defy macroscopic realism. With LGIs, correlations of measurements performed on a single system at different times are described. The measured value of K = 1.120 +/- 0.007, obtained in a neutron interferometric experiment, is clearly above the limit K = 1 predicted by macro-realistic theories.