Quantum Nondemolition Measurement Enables Macroscopic Leggett-Garg Tests

Budroni, C.; Vitagliano, G.; Colangelo, Gilberto; Sewell, R. J.; Gühne, O.; Tóth, G.; Mitchell, M. W. (2015). Quantum Nondemolition Measurement Enables Macroscopic Leggett-Garg Tests. Physical review letters, 115(20) American Physical Society 10.1103/PhysRevLett.115.200403

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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 nondemolition (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 recreate quantum backaction in his or her account of measurement.

Item Type:

Journal Article (Original Article)

Division/Institute:

10 Strategic Research Centers > Albert Einstein Center for Fundamental Physics (AEC)
08 Faculty of Science > Institute of Theoretical Physics

UniBE Contributor:

Colangelo, Gilberto

Subjects:

500 Science > 530 Physics

ISSN:

0031-9007

Publisher:

American Physical Society

Language:

English

Submitter:

Esther Fiechter

Date Deposited:

20 Nov 2015 15:44

Last Modified:

20 Nov 2015 15:44

Publisher DOI:

10.1103/PhysRevLett.115.200403

BORIS DOI:

10.7892/boris.73159

URI:

https://boris.unibe.ch/id/eprint/73159

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