Widely tunable parametric amplifier based on a superconducting quantum interference device array resonator

Abstract

The authors create a Josephson parametric amplifier from a transmission line resonator whose inner conductor is made from a series of superconducting quantum interference device (SQUID) array. By changing the magnetic flux through the SQUID loops, they are able to adjust the circuit’s resonance frequency and the center of the amplified band between 4 and $7.8\mathrm{GHz}$ . They observe that the amplifier has gains as large as $28\mathrm{dB}$ and infers that it adds less than twice the input vacuum noise.