title: Suppressing relaxation in superconducting qubits by quasiparticle pumping.
abstract: Dynamical error suppression techniques are commonly used to improve coherence in quantum systems. They reduce dephasing errors by applying control pulses designed to reverse erroneous coherent evolution driven by environmental noise. However, such methods cannot correct for irreversible processes such as energy relaxation. We investigate a complementary, stochastic approach to reducing errors: Instead of deterministically reversing the unwanted qubit evolution, we use control pulses to shape the noise environment dynamically. In the context of superconducting qubits, we implement a pumping sequence to reduce the number of unpaired electrons (quasiparticles) in close proximity to the device. A 70% reduction in the quasiparticle density results in a threefold enhancement in qubit relaxation times and a comparable reduction in coherence variability.
authors.affiliation: Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. simongus@mit.edu.
authors.forename: Simon
authors.initials: S
authors.lastname: Gustavsson
authors.affiliation: Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.forename: Fei
authors.initials: F
authors.lastname: Yan
authors.affiliation: Forschungszentrum Jülich, Peter Grünberg Institut (PGI-2), 52425 Jülich, Germany.
authors.forename: Gianluigi
authors.initials: G
authors.lastname: Catelani
authors.affiliation: Microtechnology and Nanoscience, Chalmers University of Technology, SE-41296 Gothenburg, Sweden.
authors.forename: Jonas
authors.initials: J
authors.lastname: Bylander
authors.affiliation: Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.forename: Archana
authors.initials: A
authors.lastname: Kamal
authors.affiliation: Massachusetts Institute of Technology (MIT) Lincoln Laboratory, 244 Wood Street, Lexington, MA 02420, USA.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Birenbaum
authors.affiliation: Massachusetts Institute of Technology (MIT) Lincoln Laboratory, 244 Wood Street, Lexington, MA 02420, USA.
authors.forename: David
authors.initials: D
authors.lastname: Hover
authors.affiliation: Massachusetts Institute of Technology (MIT) Lincoln Laboratory, 244 Wood Street, Lexington, MA 02420, USA.
authors.forename: Danna
authors.initials: D
authors.lastname: Rosenberg
authors.affiliation: Massachusetts Institute of Technology (MIT) Lincoln Laboratory, 244 Wood Street, Lexington, MA 02420, USA.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Samach
authors.affiliation: Massachusetts Institute of Technology (MIT) Lincoln Laboratory, 244 Wood Street, Lexington, MA 02420, USA.
authors.forename: Adam P
authors.initials: AP
authors.lastname: Sears
authors.affiliation: Massachusetts Institute of Technology (MIT) Lincoln Laboratory, 244 Wood Street, Lexington, MA 02420, USA.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Weber
authors.affiliation: Massachusetts Institute of Technology (MIT) Lincoln Laboratory, 244 Wood Street, Lexington, MA 02420, USA.
authors.forename: Jonilyn L
authors.initials: JL
authors.lastname: Yoder
authors.affiliation: Department of Physics, University of California, Berkeley, CA 94720, USA.
authors.forename: John
authors.initials: J
authors.lastname: Clarke
authors.affiliation: Massachusetts Institute of Technology (MIT) Lincoln Laboratory, 244 Wood Street, Lexington, MA 02420, USA.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Kerman
authors.affiliation: The Institute of Physical and Chemical Research (RIKEN), Wako, Saitama 351-0198, Japan.
authors.forename: Fumiki
authors.initials: F
authors.lastname: Yoshihara
authors.affiliation: Center for Emergent Matter Science (CEMS), RIKEN, Wako, Saitama 351-0198, Japan.|Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8904, Japan.
authors.forename: Yasunobu
authors.initials: Y
authors.lastname: Nakamura
authors.affiliation: Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.forename: Terry P
authors.initials: TP
authors.lastname: Orlando
authors.affiliation: Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.|Massachusetts Institute of Technology (MIT) Lincoln Laboratory, 244 Wood Street, Lexington, MA 02420, USA.|Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.forename: William D
authors.initials: WD
authors.lastname: Oliver