Null weak values: can the properties of a physical system vanish ?

Oded Zilberberg, Alessandro Romito, Yuval Gefen

A. Matzkin

Quentin Duprey, A. Matzkin

We discuss the preceding Comment [D. Sokolovski, preceding Comment, Phys. Rev. A 97, 046102 (2018)] and conclude that the arguments given there against the relevance of null weak values as representing the absence of a system property are not compelling. We give an example in which the transition matrix elements that make the projector weak values vanish are the same ones that suppress detector clicks in strong measurements. Whether weak values are taken to account for the past of a quantum system or not depend on general interpretational commitments of the quantum formalism itself rather than on peculiarities of the weak measurements framework.

Quentin Duprey, A. Matzkin

Nondestructive weak measurements (WMs) made on a quantum particle are useful in order to extract information as the particle evolves from a prepared state to a finally detected state. The physical meaning of this information has been open to debate, particularly in view of the apparent discontinuous trajectories of the particle recorded by WMs. In this work we investigate the properties of vanishing weak values for projection operators as well as general observables. We then analyze the implications when inferring the past of a quantum particle. We provide a nonoptical example for which apparent discontinuous trajectories are obtained by WMs. Our approach is compared to previous results.

Lev Vaidman A

D. Sokolovski

In a recent paper [Phys. Rev. A 95, 032110 (2017)], Duprey and Matzkin investigated the meaning of vanishing weak values and their role in the retrodiction of the past of a preselected and postselected quantum system in the presence of interference. Here we argue that any proposition regarding the weak values should be understood as a statement about the probability amplitudes. With this in mind, we revisit some of the conclusions reached in Duprey and Matzkin's work.