Optimizing quantum process tomography with unitary2-designs

A J Scott
2008 Journal of Physics A: Mathematical and Theoretical  
We show that weighted unitary 2-designs define optimal measurements on the system-ancilla output state for ancilla-assisted process tomography of unital quantum channels. Examples include complete sets of mutually unbiased unitary-operator bases. Each of these specifies a minimal series of optimal orthogonal measurements. General quantum channels are also considered.
doi:10.1088/1751-8113/41/5/055308 fatcat:erxddthszzdajnixsyty3oisja