title: On the general constraints in single qubit quantum process tomography.
abstract: We briefly review single-qubit quantum process tomography for trace-preserving and nontrace-preserving processes, and derive explicit forms of the general constraints for fitting experimental data. These forms provide additional insight into the structure of the process matrix. We illustrate this with several examples, including a discussion of qubit leakage error models and the intuition which can be gained from their process matrices.
authors.affiliation: Laboratory for Physical Sciences, 8050 Greenmead Drive, College Park, Maryland 20740, USA.
authors.forename: Ramesh
authors.initials: R
authors.lastname: Bhandari
authors.affiliation: Oak Ridge National Laboratory, One Bethel Valley Road, P.O. Box 2008, MS-6418, Oak Ridge, Tennessee 37831, USA.
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Peters