Amplification, squeezing and spectroscopy with a kinetic inductance parametric amplifier

Speaker: Jarryd Pla
Affiliation: University of NSW

Abstract

Degenerate microwave amplifiers offer the potential to perform a measurement of weak microwave signals free from any degradation to their signal-to-noise ratio, a benefit afforded by the quantum mechanics of their phase sensitive gain [1]. The degenerate parametric amplifier may even be used to enhance the signal-to-noise ratio of a weak measurement by squeezing the background noise fluctuations beneath the vacuum level. Consequently, parametric amplifiers have featured in several recent sensitivity breakthroughs across multiple fields. These include the detection of gravitational waves, the search for dark matter and high-sensitivity electron spin resonance spectroscopy. In this seminar I will present a novel microwave degenerate parametric amplifier based on the non-linear superconducting phenomenon of kinetic inductance. The device (known as a KIPA) is a simple and robust quantum-limited phase sensitive amplifier, which is well-described by theory and shows potential as a highly effective tool for the production of squeezed microwave light.

I will further discuss how the amplifier can be used in electron spin resonance (ESR) spectroscopy to enhance the sensitivity for measurements of small spin ensembles. As an extension to previous work where Josephson Parametric Amplifiers have been incorporated as additional elements in the detection chain of ESR spectrometers [2-4], we show that this new degenerate parametric amplifier can be directly coupled to spin systems, serving simultaneously as the inductive detection resonator and first-stage amplifier. Finally, operating the amplifier at large gains reveals a new mechanism for detecting spin echoes which causes the parametric amplifier to transition to the parametric oscillation regime, where it generates a large sustained self-oscillation signal.

^{[1] C. M. Caves, Quantum limits on noise in linear amplifiers, Physical Review D 26:18179 (1982)
[2] A. Bienfait, et. al. Reaching the quantum limit of sensitivity in electron spin resonance. Nature Nano. 11(3):253 (2016)
[3] C. Eichler, et. al. Electron spin resonance at the level of 104 spins using low impedance superconducting resonators. Phys. Rev. Lett. 118(3): 037701 (2017)
[4] V. Ranjan, et. al. Electron spin resonance spectroscopy with femtoliter detection volume. Appl. Phys. Lett. 116:184002 (2020)}