Flux-Driven Josephson Traveling-Wave Parametric Amplifier

We develop a concept for a traveling-wave parametric amplifier driven by a magnetic flux wave. The circuit consists of a serial array of symmetric dc superconducting quantum-interference devices coupled inductively to a separate superconducting LC transmission line carrying the pump wave. The adjusted phase velocity of the pump flux wave of frequency omega(p) ensures amplification of the signal (omega(s)) and idler (omega(i)) waves, with frequencies obeying the relation omega(s) + omega(i) = omega(p). The advantage of the proposed flux-driven linear circuit includes a large gain over a wide frequency range and overcoming of the pump depletion problem. Unlike conventional traveling-wave amplifiers, the signal and pump in the proposed circuit are applied to different ports, what can greatly simplify the whole measurement setup. The experimental parameters and characteristics of this amplifier are evaluated and show promise for applications in quantum-information single-photon circuits.