A scheme for performing strong and weak sequential measurements of non-commuting observables

Aharon Brodutch, Eliahu Cohen

Research output: Contribution to journalArticlepeer-review


Quantum systems usually travel a multitude of different paths when evolving through time from an initial to a final state. In general, the possible paths will depend on the future and past boundary conditions, as well as the system’s dynamics. We present a gedanken experiment where a single system apparently follows mutually exclusive paths simultaneously, each with probability one, depending on which measurement was performed. This experiment involves the measurement of observables that do not correspond to Hermitian operators. Our main result is a scheme for measuring these operators. The scheme is based on the erasure protocol [Brodutch and Cohen (Phys. Rev. Lett. 116:070404, 2016)] and allows a wide range of sequential measurements at both the weak and strong limits. At the weak limit the back action of the measurement cannot be used to account for the surprising behaviour and the resulting weak values provide a consistent yet strange account of the system’s past.

Original languageEnglish
Pages (from-to)13-27
Number of pages15
JournalQuantum Studies: Mathematics and Foundations
Issue number1
StatePublished - 1 Apr 2017
Externally publishedYes


  • Hermitian Operator
  • Projective Measurement
  • Sequential Measurement
  • Strong Measurement
  • Weak Measurement

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics
  • Mathematical Physics


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