Quantum Sensing with Superfluid Helium: Hardware Design and Phonon Transport Simulation

Abstract

Neutrinos are abundant fundamental particles that rarely interact with matter, making them extremely difficult to detect and study. Yet we hope to study them because they can yield insights into the origin of matter and the evolution of the universe. Despite the elusive nature of neutrinos, nuclear reactors, which produce an immense flux of reactor antineutrinos as a byproduct of beta decay, enabled the first detection of neutrinos and have been used to safely monitor nuclear reactor facilities. However, current neutrino detectors lack the capability to measure most neutrinos from nuclear activities, and the multi-ton weight of existing detectors constrains future scalability and portability. In this thesis, we investigate the initial design and simulation of devices for a new approach: the quantum sensing of neutrinos with superfluid helium. Adopting techniques from dark matter experiments, we utilize CaWO4 as a target crystal, coated in a thin film of superfluid helium, to study the quantum evaporation of helium atoms induced by quasiparticle excitations. We develop a toy model to approximate the quantum evaporation efficiency, yielding simulated results consistent with previous calculations used in dark matter experiments. Additionally, we prepared and designed hardware and apparatuses for the ongoing construction of the quantum sensor, including a high-current printed circuit board, gold-plating procedures, and thin-film cesium depositors. Our work lays the foundation for realizing the first stage of the quantum sensor, upon which future continuations will build to realize initial experiments.