Abstract
The problem of distinguishing two unitary transformations, or quantum gates, is analyzed and a function reflecting their statistical distinguishability is found. Given two unitary operations, and , it is proved that there always exists a finite number such that and are perfectly distinguishable, although they were not in the single-copy case. This result can be extended to any finite set of unitary transformations. Finally, a fidelity for one-qubit gates, which satisfies many useful properties from the point of view of quantum information theory, is presented.
- Received 7 March 2001
DOI:https://doi.org/10.1103/PhysRevLett.87.177901
©2001 American Physical Society