Laser Physics

The discontinuous trajectories of a photon are produced by the continuous propagating paths

Qi-Zhang Yuan, Shu-Jie Zhou, Xun‐Li Feng

Published Sep 10, 2020• 0 citations

Abstract

Abstract A new type of four-path interferometer is proposed to investigate the nature of the ‘discontinuous trajectories’ of a photon. Our derivation shows that the absence of ‘weak traces’, which makes the trajectories of the photon seem to be discontinuous, is actually due to the multi-path interference, and cannot be a strong criterion to say ‘The photon has not been there.’ The presence of the weak traces is a sufficient but not necessary condition for the fact that the photon has been the corresponding places. Moreover, the propagating paths of the photon must always be continuous.

DOI: 10.1088/1555-6611/abaefe

Related papers

Three-path interference of a photon and reexamination of the nested Mach-Zehnder interferometer

Qi-Zhang Yuan, Xun‐Li Feng

We present a three-path photon interferometer, theoretically investigate the behavior of the photon passing through it, and revisit the surprising experimental outcomes introduced by Danan et al. [Phys. Rev. Lett. 111, 240402 (2013)]. Our study shows that the ``discontinuous trajectory'' behavior of the photon results from the interference of the three propagation paths of the photon, which originate from the light source and end in the detector. If two of the three paths are adjusted in a destructive interference condition, there will be a zero probability domain in the overlap region of these two paths. However, these two paths can still individually interfere with the third path and contribute to the final output. In this condition, the discontinuous trajectory phenomenon appears. Our theory has a clear physical image and agrees with the experimental outcomes very well.

Physical Review AMay 3, 201917 citations

Response to the comment on “Paradox of photons disconnected trajectories being located by means of ‘weak measurements’ in the nested Mach–Zehnder interferometer” (JETP Letters 105, 152 (2017))

G. N. Nikolaev

The author of the comment on my work [1] states that the proposed modification of the scheme of the experiment reported in [2] is improper and that the experiment faithfully demonstrates a discontinuous trace of photons.It is difficult to agree with this statement because of the absence of clear and well-founded (see below).In [1], I discussed the recent experiment [2] with a nested Mach-Zehnder interferometer.The authors treated the experiment so that the past of photons is not described by continuous trajectories because photons are detected inside the inner Mach-Zehnder interferometer and are not detected outside it.The idea of a small modification of the scheme of the experiment [2] has been proposed just to detect photons at the input of the inner Mach-Zehnder interferometer.Instead of the vibration of the mirror, the direction of polarization of light is modulated in this scheme.Further, in one of the arms of the inner Mach-Zehnder interferometer, this modulation is converted into a shift of the light beam of orthogonal polarization, which is then transformed to the original polarization.The realization of the idea is as follows.A birefringent plate, a phase compensator, and two polarizers that oriented at the angle of 45° and in parallel to the initial polarization are placed in one of the arms of the inner Mach-Zehnder interferometer.The same polarizers are placed in the other two arms of the nested Mach-Zehnder interferometer.The author of the comment states that such a modification is improper because it "violates the faithfulness of the experiment because it causes different transformations of the polarization record at E into a signal at the detector, depending on the path the beam takes."The author of the comment also claims that "the signal at the detector does not present a faithful indication of the trace inside the interferometer" in the absence of con-

arXiv:1705.08721Journal of Experimental and Theoretical Physics LettersApr 1, 20177 citations

Comment on “Paradox of photons disconnected trajectories being located by means of ‘weak measurements’ in the nested Mach–Zehnder interferometer” (JETP Letters 105, 152 (2017))

L. Vaidman

The criticism of the experiment showing discontinuous traces of photons passing through a nested Mach-Zehnder interferometer is shown to be unfounded.

arXiv:1705.02137Journal of Experimental and Theoretical Physics LettersMar 31, 201717 citations

Paradox of photons disconnected trajectories being located by means of “weak measurements” in the nested Mach–Zehnder interferometer

G. N. Nikolaev

Recently, a scheme based on the method of weak measurements to register the trajectories of photons passing through a nested Mach–Zehnder interferometer was proposed [L. Vaidman, Phys. Rev. A 87 , 052104 (2013)] and then realized [A. Danan, D. Farfurnik, S. Bar-Ad, et al., Phys. Rev. Lett. 111 , 240402 (2013)]. Interpreting the results of the experiment, the authors concluded that “the photons do not always follow continuous trajectories.” It is shown in this work that these results can be easily and clearly explained in terms of traditional classical electrodynamics or quantum mechanics implying the continuity of all possible paths of photons. Consequently, a new concept of disconnected trajectories proposed by the authors of work [Phys. Rev. Lett. 111 , 240402 (2013)] is unnecessary.

arXiv:1706.00662Journal of Experimental and Theoretical Physics LettersFeb 1, 201723 citations

Erasing the past of photons

Jinxian Guo, Qi-Zhang Yuan, Yuan Wu +1 more

Photons have been proved to hide their past, especially in interferometers. Recently, several surprising results have been shown in nested Mach-Zehnder interferometer(NMZI), proving that the 'weak trace' of photons can be hidden. This paper rearranges the three path interference problem which gives the general result of its output and the conditions for eliminating the weak trace. Surprisingly, such conditions strongly depend on the detection method of the output photon, as well as the phase differences and splitting ratios in the NMZI. Further analysis gives a new weak trace elimination phenomenon which is independent of the position sensitive detector. Moreover, we setup an experiment to verify the weak trace elimination conditions and demonstrate the new weak trace elimination phenomenon.

Sep 22, 20210 citations

Higher order weak values for paths in nested Mach-Zender interferometers

Shushmi Chowdhury, Jörg B. Götte

We consider weak values in the Feynman propagator framework, to gain a broader understanding of their interpretation in terms of path integrals. In particular, we examine the phenomenon of seemingly discontinuous paths that particles take in nested Mach-Zender interferometer experiments. We extend on existing path integral approaches for weak values by deriving expressions to model a sequence of weak measurements, and study the probe shifts across the different branches of a weak value interferometer. We apply this to scrutinise two scenarios of interest, one which treats photons as measurement apparatus via their spatial projection operators, and the second treating mirrors as probes.

arXiv:2407.06989Jul 9, 20241 citation