The shell game is a classic con, a rigged contest meant to separate a person from their money. The quantum shell game described in a new paper is meant to elucidate the role of measurement in the outcome of an experiment, separating the quantum and classical aspects clearly. This was accomplished using measurement of the spin of a nitrogen atom in a diamond, and rules out the naive idea that the act of measurement is responsible for quantum weirdness.

Another approach to probing this distinction involves strong measurements that have no classical counterpart. Richard E. George and colleagues demonstrated incompatibility of the naive classical view in measurements on a modified diamond. As they described in a new PNAS paper, the equivalent classical system is similar to the old con known as the shell game: three shells, with a pea under one of them. Here, the act of “measuring” the pea’s location has no effect on the system. But the researchers’ quantum system excludes this classical behavior well beyond reasonable doubt or random chance. [Read more….]