A cm-wave quantum noise limited resonant superconducting parametric amplifier

TL;DR

This paper introduces a superconducting resonant parametric amplifier operating at 18-27 GHz with quantum-limited noise performance, high gain, and multiple narrow frequency bands, suitable for advanced quantum and astrophysical experiments.

Contribution

The work presents a novel CSRR-based amplifier on NbTi sapphire, achieving four narrow-band resonances with high gain and low noise at millikelvin temperatures.

Findings

Maximum gain of 30 dB achieved

Added noise of 1.2 half quanta measured

Four resonances observed between 23.3 and 26.3 GHz

Abstract

Superconducting Parametric Amplifiers (SPAs) have seen great interest in recent years due to their high gain and quantum limited noise performance. Among these amplifiers, resonant SPAs have been widely developed for experiments where ultra low-noise narrow-band amplification is of interest, such as the search for Axion dark matter in particle physics and the detection of spectroscopic lines in astrophysics, while also finding applications in quantum computing. This work presents an amplifier based on a Complementary Split Ring Resonator (CSRR), patterned on a NbTi coated sapphire substrate embedded within a waveguide, designed to work at a set of four narrow frequency bands throughout K band (18-27 GHz) using the kinetic inductance of the superconducting film. The S-parameters measured at 400 mK, using a sorption cooler, show the four resonances between 23.3 and 26.3 GHz at 1 GHz spacing, with a maximum transmission on resonance of -1 dB. Four-wave mixing has been observed with each resonance, and a maximum signal gain of 30 dB has been measured, corresponding to 29 dB of insertion gain. The noise performance of the amplifier has been measured, showing an added noise of 1.2 half quanta at 400 mK. These results are relevant to high-frequency Axion dark matter experiments and help motivate the exploration of higher frequencies in quantum technologies.