Flux-driven Josephson parametric amplifier

TL;DR

This paper presents a flux-driven Josephson parametric amplifier using a superconducting resonator with a dc SQUID, achieving high gain and low noise, suitable for quantum information applications.

Contribution

The development of a flux-driven Josephson parametric amplifier with tunable frequency and high gain, demonstrating effective amplification and low noise performance.

Findings

Maximum gain of 17 dB observed

Amplification depends on phase between pump and signal

Estimated noise temperature below 0.87 K

Abstract

We have developed a Josephson parametric amplifier, comprising a superconducting coplanar waveguide resonator terminated by a dc SQUID (superconducting quantum interference device). An external field (the pump, $\sim 20$ GHz) modulates the flux threading the dc SQUID, and, thereby, the resonant frequency of the cavity field (the signal, $\sim 10$ GHz), which leads to parametric signal amplification. We operated the amplifier at different band centers, and observed amplification (17 dB at maximum) and deamplification depending on the relative phase between the pump and the signal. The noise temperature is estimated to be less than 0.87 K.