An Improved Experiment to Determine the 'Past of a Particle' in the Nested Mach-Zehnder Interferometer

A. Ben-Israel, L. Knips, J. Dziewior, J. Meinecke, A. Danan, H. Weinfurter, L. Vaidman

Research output: Contribution to journalArticlepeer-review

Abstract

We argue that the modification proposed by Li et al. [Chin. Phys. Lett. 32 (2015) 050303 to the experiment of Danan et al. [Phys. Rev. Lett. 111 (2013) 240402] does not test the past of the photon as characterized by local weak traces. Instead of answering the questions: (i) were the photons in ? (ii) were the photons in ? and (iii) were the photons in ? the proposed experiment measures a degenerate operator answering the questions: (i) were the photons in ? and (ii) were the photons in and together? A negative answer to the last question does not tell us if photons were present in or . On the other hand, a simple variation of the proposal by Li et al. does provide conceptually better evidence for the past of the pre- and post-selected photon, but this evidence will be in agreement with the results of Danan et al.

Original languageEnglish
Article number020301
JournalChinese Physics Letters
Volume34
Issue number2
DOIs
StatePublished - Feb 2017

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