We show that, in principle, $N$-partite unitary transformations can be perfectly discriminated under local operations and classical communication despite their nonlocal properties. Based on this result, some related topics, including the construction of the appropriate quantum circuit together with the extension to general completely positive trace preserving operations, are discussed.

• Received 11 April 2007

DOI:https://doi.org/10.1103/PhysRevLett.99.170401