title: Measurement of geometric dephasing using a superconducting qubit.
abstract: A quantum system interacting with its environment is subject to dephasing, which ultimately destroys the information it holds. Here we use a superconducting qubit to experimentally show that this dephasing has both dynamic and geometric origins. It is found that geometric dephasing, which is present even in the adiabatic limit and when no geometric phase is acquired, can either reduce or restore coherence depending on the orientation of the path the qubit traces out in its projective Hilbert space. It accompanies the evolution of any system in Hilbert space subjected to noise.
authors.affiliation: Department of Physics, ETH Zurich, CH-8093 Zurich, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Berger
authors.affiliation: Department of Physics, ETH Zurich, CH-8093 Zurich, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Pechal
authors.affiliation: Department of Physics, ETH Zurich, CH-8093 Zurich, Switzerland.
authors.forename: P
authors.initials: P
authors.lastname: Kurpiers
authors.affiliation: Department of Physics, ETH Zurich, CH-8093 Zurich, Switzerland.
authors.forename: A A
authors.initials: AA
authors.lastname: Abdumalikov
authors.affiliation: Department of Physics, ETH Zurich, CH-8093 Zurich, Switzerland.
authors.forename: C
authors.initials: C
authors.lastname: Eichler
authors.affiliation: Department of Physics, ETH Zurich, CH-8093 Zurich, Switzerland.
authors.forename: J A
authors.initials: JA
authors.lastname: Mlynek
authors.affiliation: Institut für Theorie der Kondensierten Materie, Karlsruhe Institute of Technology, 76128 Karlsruhe, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Shnirman
authors.affiliation: Department of Condensed Matter Physics, The Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Yuval
authors.initials: Y
authors.lastname: Gefen
authors.affiliation: Department of Physics, ETH Zurich, CH-8093 Zurich, Switzerland.
authors.forename: A
authors.identifier: http://orcid.org/0000-0002-3476-4485
authors.initials: A
authors.lastname: Wallraff
authors.affiliation: Department of Physics, ETH Zurich, CH-8093 Zurich, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Filipp