Comparison of unitary transforms

Anna Erika Elisabeth Andersson, Igor Jex, Stephen M Barnett

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


We analyse the problem of comparing unitary transformations. The task is to decide, with minimal resources and maximal reliability, whether two given unitary transformations are identical or different. It is possible to make such. comparisons without obtaining any information about the individual transformations. Different comparison strategies are presented and compared with respect to their efficiency. With an interferometric setup, it is possible to compare two unitary transforms using only one test particle. Another strategy makes use of a two-particle singlet state. This strategy is more efficient than using a non-entangled two-particle test state, thus demonstrating the benefit of entanglement. Generalizations to higher.-dimensional transforms and to more than two transformations are made.

Original languageEnglish
Pages (from-to)2325-2338
Number of pages14
JournalJournal of Physics A: Mathematical and General
Issue number9
Publication statusPublished - 7 Mar 2003


Dive into the research topics of 'Comparison of unitary transforms'. Together they form a unique fingerprint.

Cite this