Quantum non-demolition measurement enables macroscopic Leggett-Garg tests
Abstract
We show how a test of macroscopic realism based on Leggett-Garg inequalities (LGIs) can be performed in a macroscopic system. Using a continuous-variable approach, we consider quantum non-demolition (QND) measurements applied to atomic ensembles undergoing magnetically-driven coherent oscillation. We identify measurement schemes requiring only Gaussian states as inputs and giving a significant LGI violation with realistic experimental parameters and imperfections. The predicted violation is shown to be due to true quantum effects rather than to a classical invasivity of the measurement. Using QND measurements to tighten the "clumsiness loophole" forces the stubborn macrorealist to re-create quantum back action in his or her account of measurement.
Keywords
Cite
@article{arxiv.1503.08433,
title = {Quantum non-demolition measurement enables macroscopic Leggett-Garg tests},
author = {Costantino Budroni and Giuseppe Vitagliano and Giorgio Colangelo and Robert J. Sewell and Otfried Gühne and Geza Toth and Morgan Mitchell},
journal= {arXiv preprint arXiv:1503.08433},
year = {2015}
}