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Physical Review A

Reply to “Comment on ‘One-state vector formalism for the evolution of a quantum state through nested Mach-Zehnder interferometers’ ”

Karol Bartkiewicz, Antonín Černoch, Dalibor Javůrek, Karel Lemr, Jan Soubusta, Jiŕí Svozilík

Published Mar 31, 2016• 7 citations
Publisher

Abstract

In our recent paper [Phys. Rev. A 91, 012103 (2015)] we have provided an alternative description of a highly debated experiment by Danan et al. [Phys. Rev. Lett. 111, 240402 (2013)]. The former paper has been recently commented on by Vaidman [Phys. Rev. A 93, 036103 (2016)]. In this Reply we demonstrate that the comments are either invalid or, where valid, do not affect the results of our original paper.

DOI
10.1103/physreva.93.036104

Related papers

Comment on “One-state vector formalism for the evolution of a quantum state through nested Mach-Zehnder interferometers”

Lev Vaidman A

Bartkiewicz et al. [Phys. Rev. A 91, 012103 (2015)] provided an alternative analysis of an experiment performed by Danan et al. [Phys. Rev. Lett. 111, 240402 (2013)] which presented surprising evidence regarding the past of photons passing through an interferometer. They argued that the quantity used by Danan et al. is not a suitable which-path witness, and proposed an alternative. The weaknesses of the analysis are discussed, and it is argued that the alternative, analyzed properly, provides no new predictions.

arXiv:1508.07614•Physical Review A•Mar 31, 2016•24 citations

One-state vector formalism for the evolution of a quantum state through nested Mach-Zehnder interferometers

Karol Bartkiewicz, Antonín Černoch, Dalibor Javůrek +3 more

Linear-optical interferometers play a key role in designing circuits for quantum information processing and quantum communications. Even though nested Mach-Zehnder interferometers appear easy to describe, there are occasions when they provide unintuitive results. This paper explains the results of a highly discussed experiment performed by Danan et al. [Phys. Rev. Lett. 111, 240402 (2013).] using a standard approach. We provide a simple and intuitive one-state vector formalism capable of interpreting their experiment. Additionally, we cross-checked our model with a classical-physics-based approach and found that both models are in complete agreement. We argue that the quantity used in the mentioned experiment is not a suitable which-path witness, producing seemingly contraintuitive results. To circumvent this issue, we establish a more reliable which-path witness and show that it yields well-expected outcomes of the experiment.

arXiv:1410.8454•Physical Review A•Jan 12, 2015•39 citations

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

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

Robert B. Griffiths

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)].

arXiv:1712.01895•Physical Review A•Feb 9, 2018•12 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

Comments to Asking Photons Where They Have Been (A Danan et al, Phys. Rev. Lett. 111, 240402 (2013))

B. E. Y. Svensson

I critize some of the conclusions in the paper by Danan et al, in particular their claim that '(S)ome (of the photons) have been inside the nested interferometer ... but they never entered and never left (it) ...'. A standard quantum-mechanical analysis also casts doubts on their statement that '(o)nly the description with forward and backward evolving quantum states provides a simple and intuitive picture of pre- and postselected quantum particles.'

arXiv:1402.4315•Feb 18, 2014•0 citations
In our recent paper [Phys. Rev. A 91, 012103 (2015)] we have provided an alternative description of a highly debated experiment by Danan et al. [Phys. Rev. Lett. 111, 240402 (2013)]. The former paper has been recently commented on by Vaidman [Phys. Rev. A 93, 036103 (2016)]. In this Reply we demonstrate that the comments are either invalid or, where valid, do not affect the results of our original paper.
Bartkiewicz et al. [Phys. Rev. A 91, 012103 (2015)] provided an alternative analysis of an experiment performed by Danan et al. [Phys. Rev. Lett. 111, 240402 (2013)] which presented surprising evidence regarding the past of photons passing through an interferometer. They argued that the quantity used by Danan et al. is not a suitable which-path witness, and proposed an alternative. The weaknesses of the analysis are discussed, and it is argued that the alternative, analyzed properly, provides no new predictions.
Linear-optical interferometers play a key role in designing circuits for quantum information processing and quantum communications. Even though nested Mach-Zehnder interferometers appear easy to describe, there are occasions when they provide unintuitive results. This paper explains the results of a highly discussed experiment performed by Danan et al. [Phys. Rev. Lett. 111, 240402 (2013).] using a standard approach. We provide a simple and intuitive one-state vector formalism capable of interpreting their experiment. Additionally, we cross-checked our model with a classical-physics-based approach and found that both models are in complete agreement. We argue that the quantity used in the mentioned experiment is not a suitable which-path witness, producing seemingly contraintuitive results. To circumvent this issue, we establish a more reliable which-path witness and show that it yields well-expected outcomes of the experiment.