How the result of a measurement of a component of the spin of a spin-1/2 particle can turn out to be 100

Phys. Rev. Lett. 60, 1351 – Published 4 April 1988
Yakir Aharonov, David Z. Albert, and Lev Vaidman


We have found that the usual measuring procedure for preselected and postselected ensembles of quantum systems gives unusual results. Under some natural conditions of weakness of the measurement, its result consistently defines a new kind of value for a quantum variable, which we call the weak value. A description of the measurement of the weak value of a component of a spin for an ensemble of preselected and postselected spin-(1/2 particles is presented.


  • Received 30 June 1987
  • Published in the issue dated 4 April 1988

© 1988 The American Physical Society

Authors & Affiliations

Yakir Aharonov, David Z. Albert, and Lev Vaidman

  • Physics Department, University of South Carolina, Columbia, South Carolina 29208
  • School of Physics and Astronomy, Tel-Aviv University, Ramat Aviv 69978, Israel


References (Subscription Required)

Authorization Required




Log In



Article Lookup
Paste a citation or DOI

Enter a citation
  1. Enter a citation to look up or terms to search.

    Ex: "PRL 112 068103", "Phys. Rev. Lett. 112, 068103", "10.1103/PhysRevLett.112.068103"