Interaction-free measurement

Paul Kwiat, Harald Weinfurter, Thomas Herzog, Anton Zeilinger, Mark A. Kasevich

Research output: Contribution to journalArticlepeer-review


We show that one can ascertain the presence of an object in some sense without interacting with it. One repeatedly, but weakly, tests for the presence of the object, which would inhibit an otherwise coherent evolution of the interrogating photon. The fraction of "interaction-free" measurements can be arbitrarily close to 1. Using single photons in a Michelson interferometer, we have performed a preliminary demonstration of some of these ideas.

Original languageEnglish (US)
Pages (from-to)4763-4766
Number of pages4
JournalPhysical review letters
Issue number24
StatePublished - 1995
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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