TY - JOUR AU - Knee, George C. AU - Simmons, Stephanie AU - Gauger, Erik M. AU - Morton, John J. L. AU - Riemann, Helge AU - Abrosimov, Nikolai V. AU - Becker, Peter AU - Pohl, Hans-Joachim AU - Itoh, Kohei M. AU - Thewalt, Mike L. W. AU - Briggs, G. Andrew D. AU - Benjamin, Simon C. PY - 2012 DA - 2012// TI - Violation of a Leggett–Garg inequality with ideal non-invasive measurements T2 - Nat. Comm. JO - Nature Communications SP - 6 VL - 3 IS - 606 KW - fromIPMRAS AB - 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. N1 - exported from refbase (https://db.rplab.ru/refbase/show.php?record=767), last updated on Sun, 06 May 2012 16:42:11 -0500 ID - Knee_etal2012 ER -