title: Permutationally invariant quantum tomography.
abstract: We present a scalable method for the tomography of large multiqubit quantum registers. It acquires information about the permutationally invariant part of the density operator, which is a good approximation to the true state in many relevant cases. Our method gives the best measurement strategy to minimize the experimental effort as well as the uncertainties of the reconstructed density matrix. We apply our method to the experimental tomography of a photonic four-qubit symmetric Dicke state.
authors.affiliation: Department of Theoretical Physics, The University of the Basque Country, P.O. Box 644, E-48080 Bilbao, Spain.
authors.forename: G
authors.initials: G
authors.lastname: Tóth
authors.forename: W
authors.initials: W
authors.lastname: Wieczorek
authors.forename: D
authors.initials: D
authors.lastname: Gross
authors.forename: R
authors.initials: R
authors.lastname: Krischek
authors.forename: C
authors.initials: C
authors.lastname: Schwemmer
authors.forename: H
authors.initials: H
authors.lastname: Weinfurter