title: Widely tunable, nondegenerate three-wave mixing microwave device operating near the quantum limit.
abstract: We present the first experimental realization of a widely frequency tunable, nondegenerate three-wave mixing device for quantum signals at gigahertz frequency. It is based on a new superconducting building block consisting of a ring of four Josephson junctions shunted by a cross of four linear inductances. The phase configuration of the ring remains unique over a wide range of magnetic fluxes threading the loop. It is thus possible to vary the inductance of the ring with flux while retaining a strong, dissipation-free, and noiseless nonlinearity. The device has been operated in amplifier mode, and its noise performance has been evaluated by using the noise spectrum emitted by a voltage-biased tunnel junction at finite frequency as a test signal. The unprecedented accuracy with which the crossover between zero-point fluctuations and shot noise has been measured provides an upper bound for the noise and dissipation intrinsic to the device.
authors.affiliation: Laboratoire Pierre Aigrain, Ecole Normale Supérieure, CNRS (UMR 8551), Université P. et M. Curie, rue Lhomond, 75231 Paris Cedex 05, France.
authors.forename: N
authors.initials: N
authors.lastname: Roch
authors.forename: E
authors.initials: E
authors.lastname: Flurin
authors.forename: F
authors.initials: F
authors.lastname: Nguyen
authors.forename: P
authors.initials: P
authors.lastname: Morfin
authors.forename: P
authors.initials: P
authors.lastname: Campagne-Ibarcq
authors.forename: M H
authors.initials: MH
authors.lastname: Devoret
authors.forename: B
authors.initials: B
authors.lastname: Huard