Towards High-Impedance Surface Acoustic Wave Resonators for Quantum Information Processing

Inspired by quantum circuit electrodynamics systems, quantum acoustic devices, like surface acoustic wave (SAW) resonators have emerged as powerful tools for quantum information processing in the gigahertz frequency range. Specifically, piezoelectric SAW resonators could be used to couple distant spin qubits in semiconductor quantum dots. Potential benefits of SAW resonators as quantum interconnects include the ability to operate in high magnetic fields and at elevated temperatures. However, strong spin-phonon coupling requires a large characteristic impedance associated with the SAW resonator. We discuss our efforts toward realizing SAW resonators with characteristic impedances exceeding 50Ω.  To reach such levels of impedance, we use Gaussian SAW resonators on LiNbO₃ to generate tightly confined phonon modes with strong piezoelectric coupling. Apart from the possibility of coupling distant spin qubits, these high-impedance SAW resonators may also be useful for interfacing microwave and optical photons for quantum information processing.