Comment on ‘Two-state vector formalism and quantum interference’

Abstract

Hashmi et al (2016 J. Phys. A: Math. Theor. 49 345302) claimed that the approach to the past of a quantum particle introduced by Vaidman (2013 Phys. Rev. A 87 052104) has difficulties in certain examples and that it can even be refuted. Here I reply to their criticism showing that the approach provides a good explanation for all the examples they considered. It is fully consistent with standard quantum mechanics and provides a useful tool for analyzing interference experiments.

Reply to the comment on ‘Two-state vector formalism and quantum interference’

“…In our article [2] we have shown that the theory presented by the author of the comment runs into problems when applied to systems with multiple weak measurements, and that the trick used in the theory can be used to refute it. This is challenged in the preceding comment [1] claiming that we are mistaken in the analysis of certain examples discussed in our article [2]. However, the arguments presented in the comment [1] either endorse our results, or are inconsistent with the previously proposed theory [4].…”

“…This is challenged in the preceding comment [1] claiming that we are mistaken in the analysis of certain examples discussed in our article [2]. However, the arguments presented in the comment [1] either endorse our results, or are inconsistent with the previously proposed theory [4]. With such inconsistencies the claim that we are mistaken in [2] remains insubstantial.…”

“…The author of the comment [1] (a comment to our article [2]) has previously proposed a theory of the past of the particle [3][4][5][6] in which he has made a number of paradoxical claims for a quantum particle passing through a nested Mach-Zehnder interferometer, and has attracted considerable criticism from the community [2,[7][8][9][10][11][12][13][14][15][16][17][18]. In our article [2] we have shown that the theory presented by the author of the comment runs into problems when applied to systems with multiple weak measurements, and that the trick used in the theory can be used to refute it.…”

When Photons Are Lying about Where They Have Been

“…Vaidman, together with his collaborators, performed an experiment demonstrating a surprising trace of the photons in nested interferometers [ 1 ] (see Figure 1 ). These results became the topic of a very large controversy [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 ].…”

Do neutrons disagree with photons about where they have been inside an interferometer?

“…The faint trace will be on all parts of this line, but also in a separate loop disconnected from the line. The prediction of this closed loop, which does not start at the source and does not end at the detector, generated a hot discussion [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] which only intensified [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] after the first experiment with photons [22] confirmed discontinuous trajectories.…”