title: Experimental evidence of a φ Josephson junction.
abstract: We demonstrate experimentally the existence of Josephson junctions having a doubly degenerate ground state with an average Josephson phase ψ=±φ. The value of φ can be chosen by design in the interval 0<φ<π. The junctions used in our experiments are fabricated as 0-π Josephson junctions of moderate normalized length with asymmetric 0 and π regions. We show that (a) these φ Josephson junctions have two critical currents, corresponding to the escape of the phase ψ from -φ and +φ states, (b) the phase ψ can be set to a particular state by tuning an external magnetic field, or (c) by using a proper bias current sweep sequence. The experimental observations are in agreement with previous theoretical predictions.
authors.affiliation: Physikalisches Institut and Center for Collective Quantum Phenomena in LISA, Universität Tübingen, Tübingen, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Sickinger
authors.forename: A
authors.initials: A
authors.lastname: Lipman
authors.forename: M
authors.initials: M
authors.lastname: Weides
authors.forename: R G
authors.initials: RG
authors.lastname: Mints
authors.forename: H
authors.initials: H
authors.lastname: Kohlstedt
authors.forename: D
authors.initials: D
authors.lastname: Koelle
authors.forename: R
authors.initials: R
authors.lastname: Kleiner
authors.forename: E
authors.initials: E
authors.lastname: Goldobin