Cloning and joint measurements of incompatible components of spin

Thomas Brougham, Anna Erika Elisabeth Andersson, Stephen M Barnett

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)


A joint measurement of two observables is a simultaneous measurement of both quantities upon the same quantum system. When two quantum-mechanical observables do not commute, then a joint measurement of these observables cannot be accomplished directly by projective measurements alone. In this paper we shall discuss the use of quantum cloning to perform a joint measurement of two components of spin associated with a qubit system. We introduce cloning schemes which are optimal with respect to this task. The cloning schemes may be thought to work by cloning two components of spin onto their outputs. We compare the proposed cloning machines to existing cloners.

Original languageEnglish
Article number062319
Number of pages7
JournalPhysical Review A
Issue number6
Publication statusPublished - Jun 2006


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