Is weak measurement more than an experimental tool?

Eliahu Cohen, Avshalom C. Elitzur

Quantum temporal peculiarities, involving ordinary and weak measurements, are explored. We introduce the foundations of weak measurement and outline some novel theoretical and experimental predictions derived from it. We then show how weak values, which explicitly depend on both forward and backward evolving state-vectors, can serve as important tools for gaining new insights into the nature of time.

Ruth E. Kastner

Enrico Rebufello, Fabrizio Piacentini, Alessio Avella +9 more

Abstract Since their introduction, weak measurements and weak values have served as a cornerstone for investigating quantum measurement theory, as well as a significant tool for quantum metrology and sensing. Here, it is shown how (anomalous) weak values can be reliably obtained with single quantum systems even without averaging over multiple experimental runs, thanks to a measurement protocol dubbed robust weak measurement . Specifically, robust weak measurements are exploited to extract the weak value of the polarization of heralded single photons, certifying the true single‐particle, nonclassical nature of weak values.

Prashanna Simkhada, Jean-François S. Van Huele

Dawei Lu, Aharon Brodutch, Jun Li +2 more

The ability to post-select the outcomes of an experiment is a useful theoretical concept and experimental tool. In the context of weak measurements, post-selection can lead to surprising results such as complex weak values outside the range of eigenvalues. Usually post-selection is realized by a projective measurement, which is hard to implement in ensemble systems such as NMR. We demonstrate the first experiment of a weak measurement with post-selection on an NMR quantum information processor. Our setup is used for measuring complex weak values and weak values outside the range of eigenvalues. The scheme for overcoming the problem of post-selection in an ensemble quantum computer is general and can be applied to any circuit-based implementation. This experiment paves the way for studying and exploiting post-selection and weak measurements in systems where projective measurements are hard to realize experimentally.

Lev Vaidman A