Precision Measurements for Fundamental Physics*

Abstract:

Recent theoretical and experimental developments have driven the search for the axion, a hypothetical particle whose existence would account for the otherwise surprising charge-parity symmetry observed in the strong nuclear force. Furthermore, axions production in the early universe would also account for the observed abundance of dark matter.  Detecting axions, however, remains an extraordinary challenge because their feeble coupling to ordinary matter produces exceptionally weak signals. In this talk, I will present our latest advancements in quantum-enhanced sensing techniques specifically tailored for microwave-frequency axion haloscope experiments. By leveraging superconducting circuits and Josephson parametric amplifiers, we push sensitivity below the standard quantum limit for measuring the state of an electromagnetic mode in a resonant cavity. In particular, we squeeze the quantum fluctuations of this resonant mode, which forms the background noise that obscures the axion signal. Our first result demonstrated a two-fold increase in the rate at which an axion haloscope can tune through frequency, which corresponds to the unknown rest mass of the axion. I will describe experimental progress in achieving further improvements to this quantum enhanced search rate.  Finally, I will discuss the extension of our quantum sensor technology to other fundamental physics applications.

Portions of this work are part of the HAYSTAC collaboration.