2011/04/30 by George C. Knee, Stephanie Simmons, Erik M. Gauger +9 · 2 citations
Physics and Astronomy · #quant-ph
paper · pdf · doi:10.1038/ncomms1614
published as Nat. Commun. 3:606 (2012) · 6+4 pages. Supplementary Methods section included
arxiv created 2011/11/30 · arxiv updated 2012/01/04
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.