Dissertation

Cavities for light and sound: a cavity-enhanced platform for quantum acoustics

Surface acoustic waves (SAWs) are mechanical waves that travel along the surface of a material and find many applications in modern technologies due to the ease of excitation on piezoelectric substrates via interdigital transducers (IDTs).

Author: M. Fisicaro
Date: 29 October 2024
Links: Thesis in Leiden Repository

For example, they are used in telecommunications to create ultra-high-frequency electronic filters. Due to their long coherence times and their ability to interact with many different quantum systems, SAWs are also used in quantum physics research, where they can couple to a variety of two-level systems, such as superconducting qubits, NV centers, and quantum dots. In this thesis, we work with SAW cavities at GHz frequencies on GaAs. First, we develop a fiber-based scanning Michelson interferometer to image the acoustic field distribution inside the cavity. With this unique setup, we can disentangle complex transverse-mode profiles and image spurious bulk acoustic waves, enabling a novel way to optimize SAW devices. Next, we observe for the first time the dynamic Talbot effect from a SAW oscillating grating. The demonstration of this effect enables a new, non-interferometric way to measure surface acoustic waves. Finally, we develop an actively stabilized open-access optical microcavity with a mechanical stability of a few picometers when operated in a closed-cycle cryostat. The combination of this novel setup with a SAW cavity will enable single phonon detection.