Weak Measurements: Typical Weak and Superweak Values

Abstract

Weak value is a physical property of a quantum system which manifests itself through a weak measurement using different pre-and post-selected ensembles of the system. The weak values of an operator may differ significantly from its eigenvalues and can even lie outside the spectrum if it is bound: they can be 'superweak'. The latter, originating due to a coherent superposition of waves, may appear as a 'supershift' on the measuring device. This property has potential application in the amplification and detection of extremely weak signals.