title: Aharonov-Casher-effect suppression of macroscopic tunneling of magnetic flux.
abstract: We suggest a system in which the amplitude of macroscopic flux tunneling can be modulated via the Aharonov-Casher effect. The system is an rf SQUID with the Josephson junction replaced by a Bloch transistor--two junctions separated by a small superconducting island on which the charge can be induced by an external gate voltage. When the Josephson coupling energies of the junctions are equal and the induced charge is q = e, destructive interference between tunneling paths brings the flux tunneling rate to zero. The device may also be useful as a qubit for quantum computation.
authors.affiliation: Department of Physics and Astronomy, The State University of New York at Stony Brook, Stony Brook, New York 11794-3800, USA.
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Friedman
authors.forename: D V
authors.initials: DV
authors.lastname: Averin