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arXiv:1712.01895 · Physical Review A

Reply to “Comment on ‘Particle path through a nested Mach-Zehnder interferometer' ”

Robert B. Griffiths

Published Feb 9, 2018• 12 citations
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Abstract

While much of the technical analysis in the preceding Comment is correct, in the end it confirms the conclusion reached in my previous work [Phys. Rev. A 94, 032115 (2016)]: A consistent histories analysis provides no support for the claim of counterfactual quantum communication put forward by Salih et al. [Phys. Rev. Lett. 110, 170502 (2013)].

DOI
10.1103/physreva.97.026102

Related papers

Reply to Comment [axXiv:1610.07734] by L. Vaidman on "Particle path through a nested Mach-Zehnder interferometer" [R. B. Griffiths, Phys. Rev. A 94 (2016) 032115]

Robert B. Griffiths

The correctness of the consistent histories analysis of weakly interacting probes, related to the path of a particle, is maintained against the criticisms in the Comment, and against the alternative approach described there, which receives no support from standard (textbook) quantum mechanics.

arXiv:1704.03010•Apr 10, 2017•1 citation

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

Hatim Salih

In a recent paper [Phys. Rev. A 94, 032115 (2016)], Griffiths questioned---based on an interesting consistent-histories (CH) argument---the counterfactuality, for one of the bit choices, of the protocol of Salih et al. for communicating without sending physical particles [Phys. Rev. Lett. 110, 170502 (2013)]. Here, we first show that for the Mach-Zehnder version used to explain our protocol, contrary to Griffiths's claim, no family of consistent histories exists where any history has the photon traveling through the communication channel, thus rendering the question of whether the photon was in the communication channel meaningless from a CH viewpoint. We then show that for the actual Michelson-type protocol, there is a consistent-histories family for each cycle that includes histories where the photon travels through the communication channel. We show that the probability of finding the photon in the communication channel at any time is zero---proving complete counterfactuality.

arXiv:1608.01640•Physical Review A•Feb 9, 2018•17 citations

Reply to “Comment on ‘Particle path through a nested Mach-Zehnder interferometer’ ”

Robert B. Griffiths

The correctness of the consistent histories analysis of weakly interacting probes, related to the path of a particle, is maintained against the criticisms in the Comment, and against the alternative approach described there, which receives no support from standard (textbook) quantum mechanics.

Physical Review A•Jun 28, 2017•10 citations

Particle path through a nested Mach-Zehnder interferometer

Robert B. Griffiths

Possible paths of a photon passing through a nested Mach-Zehnder interferometer on its way to a detector are analyzed using the consistent histories formulation of quantum mechanics, and confirmed using a set of weak measurements (but not weak values). The results disagree with an analysis by Vaidman [Phys. Rev. A 87, 052104 (2013)], and agree with a conclusion reached by Li et al. [Phys. Rev. A 88, 046102 (2013)]. However, the analysis casts serious doubt on the claim of Salih et al. (whose authorship includes Li et al.) [Phys. Rev. Lett. 110, 170502 (2013)] to have constructed a protocol for counterfactual communication: a channel which can transmit information even though it contains a negligible number of photons.

arXiv:1604.04596•Physical Review A•Sep 16, 2016•79 citations

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

Lev Vaidman A

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.

Physical Review A•Jun 28, 2017•36 citations

Particle path(s) through a nested Mach-Zehnder interferometer: Reply to Griffiths

Lev Vaidman A

Griffiths [Phys. Rev. A 94, 032115 (2016)] analyzed, in the framework of 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 analysis of experiments with weak probes is unfounded.

arXiv:1610.07734•Oct 25, 2016•2 citations
While much of the technical analysis in the preceding Comment is correct, in the end it confirms the conclusion reached in my previous work [Phys. Rev. A 94, 032115 (2016)]: A consistent histories analysis provides no support for the claim of counterfactual quantum communication put forward by Salih et al. [Phys. Rev. Lett. 110, 170502 (2013)].
In a recent paper [Phys. Rev. A 94, 032115 (2016)], Griffiths questioned---based on an interesting consistent-histories (CH) argument---the counterfactuality, for one of the bit choices, of the protocol of Salih et al. for communicating without sending physical particles [Phys. Rev. Lett. 110, 170502 (2013)]. Here, we first show that for the Mach-Zehnder version used to explain our protocol, contrary to Griffiths's claim, no family of consistent histories exists where any history has the photon traveling through the communication channel, thus rendering the question of whether the photon was in the communication channel meaningless from a CH viewpoint. We then show that for the actual Michelson-type protocol, there is a consistent-histories family for each cycle that includes histories where the photon travels through the communication channel. We show that the probability of finding the photon in the communication channel at any time is zero---proving complete counterfactuality.
Possible paths of a photon passing through a nested Mach-Zehnder interferometer on its way to a detector are analyzed using the consistent histories formulation of quantum mechanics, and confirmed using a set of weak measurements (but not weak values). The results disagree with an analysis by Vaidman [Phys. Rev. A 87, 052104 (2013)], and agree with a conclusion reached by Li et al. [Phys. Rev. A 88, 046102 (2013)]. However, the analysis casts serious doubt on the claim of Salih et al. (whose authorship includes Li et al.) [Phys. Rev. Lett. 110, 170502 (2013)] to have constructed a protocol for counterfactual communication: a channel which can transmit information even though it contains a negligible number of photons.