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arXiv · 1104.0238

Violation of a Leggett-Garg inequality with ideal non-invasive measurements

George C. Knee·Stephanie Simmons·Erik M. Gauger·John J. L. Morton·Helge Riemann·Nikolai V. Abrosimov·Peter Becker·Hans-Joachim Pohl·Kohei M. Itoh·Mike L. W. Thewalt·G. Andrew D. Briggs·Simon C. Benjamin
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Abstract

The quantum superposition principle states that an entity can exist in two different states simultaneously, counter to our 'classical' intuition. Is it possible to understand a given system's behaviour without such a concept? A test designed by Leggett and Garg can rule out this possibility. The test, originally intended for macroscopic objects, has been implemented in various systems. However to-date no experiment has employed the 'ideal negative result' measurements that are required for the most robust test. Here we introduce a general protocol for these special measurements using an ancillary system which acts as a local measuring device but which need not be perfectly prepared. We report an experimental realisation using spin-bearing phosphorus impurities in silicon. The results demonstrate the necessity of a non-classical picture for this class of microscopic system. Our procedure can be applied to systems of any size, whether individually controlled or in a spatial ensemble.

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George C. Knee, Stephanie Simmons, Erik M. Gauger, John J. L. Morton, Helge Riemann, Nikolai V. Abrosimov, Peter Becker, Hans-Joachim Pohl, Kohei M. Itoh, Mike L. W. Thewalt, G. Andrew D. Briggs, Simon C. Benjamin. 2011-04-01. Violation of a Leggett-Garg inequality with ideal non-invasive measurements. https://doi.org/10.1038/ncomms1614

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