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

2012; Nature Portfolio; Volume: 3; Issue: 1 Linguagem: Inglês

10.1038/ncomms1614

2041-1723

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

Advanced Thermodynamics and Statistical Mechanics

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 realization 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. Quantum mechanics predicts that objects can simultaneously exist in a superposition of two states. Kneeet al.propose and demonstrate experimentally a protocol which fully confirms this prediction, by testing the so-called Leggett–Garg inequality in a non-invasive manner.