Josephson Traveling-Wave Parametric Amplifier with Three-Wave Mixing

We develop a concept of the traveling-wave Josephson parametric amplifier exploiting quadratic nonlinearity of a serial array of one-junction superconducting quantum interference devices (SQUIDs) embedded in a superconducting transmission line. The external magnetic flux applied to the SQUIDs makes it possible to efficiently control the shape of their current-phase relation and, hence, the balance between quadratic and cubic (Kerr-like) nonlinearities. This property allows us to operate in the favorable three-wave-mixing mode with a minimal phase mismatch, an exponential dependence of the power gain on number of sections N, a large bandwidth, a high dynamic range, and substantially separated signal (omega(s)) and pump (omega(p)) frequencies obeying the relation omega(s) + omega(i) = omega(p) where omega(i) is the idler frequency. An estimation of the amplifier characteristics with typical experimental parameters, a pump frequency of 12 GHz, and N = 300 yields a flat gain of 20 dB in the bandwidth of 5.6 GHz.