Investigating the `Past of a Particle' without disturbing it

TL;DR

This paper defends a quantum experiment that traces a particle’s past without disturbance, countering recent claims that it was flawed, and confirms the original method's validity.

Contribution

The authors demonstrate that the recent critique of the nested Mach-Zehnder interferometer experiment is incorrect and that the original approach remains valid without modifications.

Findings

The critique claiming the experiment's failure is false.

The original experiment effectively determines a particle's past.

No modification to the original experiment is necessary.

Abstract

In a recent article [Chin. Phys. Lett. 34, 020301 (2017)], Ben-Israel et al. have claimed that the experiment proposed in [Chin. Phys. Lett. 32, 050303 (2015)] to determine the past of a quantum particle in a nested Mach-Zehnder interferometer does not work, and they have proposed a modification to the experiment. We show that their claim is false, and the modification is not required.