Alex Matzkin (CNRS/Université de Cergy-Pontoise)

Title: Can the properties of a quantum system vanish?

Abstract:

The Weak Measurements approach is a framework based on implementing non-destructive, non-perturbing measurements on a quantum system as the system evolves from an initially prepared state to a final state obtained by performing a standard measurement. The result of a weak measurement is called the “weak value” of the weakly measured observable. Weak values have peculiar features. In particular, a vanishing weak value means that the corresponding system property cannot be found at the location where the observable was weakly measured. This may have striking consequences, like not being able to detect a particle inside an interferometer although it went in and out, or observing a spatial separation between a particle and one of its properties. I will describe situations in which quantum properties appear to “vanish” and I will put forward an explanation based on the analysis of null weak values.