Photons can tell “contradictory” answer about where they have been
Department of Physics, Mathematics and Science College of Shanghai Normal University, 200234, Shanghai, China
Accepted: 9 January 2023
Published online: 23 January 2023
In this paper we propose a modified nested Mach–Zehnder interferometer scheme which may be helpful to determine the relation between the measurable signal and a photon’s travel history. In the original scheme presented by Danan et al. (Phys. Rev. Lett. 111:240402, 2013), the mirrors in the nested Mach–Zehnder interferometer vibrate at different frequencies which can be read out from the output signal. These frequency signals are regarded as the “traces” of photon passing through the interferometer, and the presence or absence of a certain frequency is claimed to be the criterion of whether or not the photon has reflected off the related mirror. In this paper we propose a modified scheme, in which one single mirror vibrates around two axes at different frequencies. The interferometer can be adjusted to make either of the frequencies present in the output, while the other is absent. The result shows that the absence of a certain frequency does not mean the photon has not reflected off the related mirror and consequently does not indicate a “discontinuous trajectory.”
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