Quantum state separation, unambiguous discrimination and exact cloning

A. Chefles, S.M. Barnett

Research output: Contribution to journalArticlepeer-review

65 Citations (Scopus)


Unambiguous discrimination and exact cloning reduce the square-overlap between quantum states, exemplifying the more general type of procedure we term state separation. We obtain the maximum probability with which two equiprobable quantum states can be separated by an arbitrary degree, and find that the established bounds on the success probabilities for discrimination and cloning are special cases of this general bound. The latter also gives the maximum probability of successfully producing N exact copies of a quantum system whose state is chosen secretly from a known pair, given M initial realizations of the state, where N > M. We also discuss the relationship between this bound and that on unambiguous state discrimination.
Original languageEnglish
Pages (from-to)10097-10103
Number of pages6
JournalJournal of Physics A: Mathematical and Theoretical
Issue number50
Publication statusPublished - 1998


  • quantum state separation
  • exact cloning
  • physics
  • quantum states


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