Universality of local weak interactions and its application for interferometric alignment

Jan Dziewior, Lukas Knips, Demitry Farfurnik, Katharina Senkalla, Nimrod Benshalom, Jonathan Efroni, Jasmin Meinecke, Shimshon Bar-Ad, Harald Weinfurter, Lev Vaidman*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The modification of the effect of interactions of a particle as a function of its preselected and postselected states is analyzed theoretically and experimentally. The universality property of this modification in the case of local interactions of a spatially preselected and postselected particle has been found. It allowed us to define an operational approach for the characterization of the presence of a quantum particle in a particular place: the way it modifies the effect of local interactions. The experiment demonstrating this universality property provides an efficient interferometric alignment method, in which the position of the beam on a single detector throughout one phase scan yields all misalignment parameters.

Original languageEnglish
Pages (from-to)2881-2890
Number of pages10
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number8
StatePublished - 19 Feb 2019


  • Optics alignment
  • Quantum experiments
  • Quantum measurement
  • Quantum physics
  • Weak measurements

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