Features of Sequential Weak Measurements

          @misc{ pirsa_PIRSA:16060053,
            doi = {10.48660/16060053},
            url = {https://pirsa.org/16060053},
            author = {},
            keywords = {Quantum Foundations},
            language = {en},
            title = {Features of Sequential Weak Measurements},
            publisher = {Perimeter Institute},
            year = {2016},
            month = {jun},
            note = {PIRSA:16060053 see, \url{https://pirsa.org}}
          }
          

Abstract

I discuss the outcome statistics of sequential weak measurement of general observables. In sequential weak measurement of canonical variables, without post-selection, correlations yield the corresponding correlations of the Wigner function. Outcome correlations in spin-1/2 sequential weak measurements without post-selection coincide with those in strong measurements, they are constrained kinematically so that they yield as much information as single measurements. In sequential weak measurements with post-selection, a new anomaly occurs, different from the weak value anomaly in single weak measurements. I consider trivial post-selection, i.e.: re-selection |f>=|i>, which should intuitively not differ from no post-selection since weak measurements are considered non-invasive. Indeed, re-selection does not matter, compared with no-selection, for single weak measurement. It does so, however, for sequential ones. I illustrate it in spin-1/2 weak measurement.