Comment on “Particle path through a nested Mach-Zehnder interferometer”

Griffiths [Phys. Rev. A 94, 032115 (2016)] analyzed, in the framework of a consistent histories interpretation, the controversy regarding the approach to the past of a quantum particle introduced by Vaidman [Phys. Rev. A 87, 052104 (2013)]. I argue that Griffith's criticism of my approach using an analysis of experiments with weak probes is unfounded.

Figure 1

(a) Nested Mach-Zehnder interferometer. The inner interferometer is tuned such that there is a destructive interference towards $E$. (b) The location of the particle detected by $D_1$ inside the interferometer according to Li et al. [2]. (c) The location of the particle detected by $D_1$ inside the interferometer according to Vaidman [3]. (d) Counts of the triggered weak probes in paths of the interferometer experiment performed on the ensemble of ${10}^7$ particles started at source $S$ and postselected in detector $D_1$.