Integrated phononic waveguides in diamond
Sophie Weiyi Ding, Benjamin Pingault, Linbo Shao, Neil Sinclair, Bartholomeus Machielse, Cleaven Chia, Smarak Maity, Marko Lončar
Abstract
Efficient generation, guiding, and detection of phonons, or mechanical vibrations, are of interest in various fields, including radio-frequency communication, sensing, and quantum information. Diamond is a useful platform for phononics because of the presence of strain-sensitive spin qubits, and its high Young's modulus, which allows for low-loss gigahertz devices. We demonstrate a diamond phononic waveguide platform for generating, guiding, and detecting gigahertz-frequency surface acoustic wave (SAW) phonons. We generate SAWs using interdigital transducers integrated on $\mathrm{Al}\mathrm{N}$/diamond and observe SAW transmission at 4--5 GHz through both ridge and suspended waveguides, with wavelength-scale cross sections (approximately 1 ${\mathrm{m}}^{2}$) to maximize spin-phonon interaction. This work is a crucial step for developing acoustic components for quantum phononic circuits with strain-sensitive color centers in diamond.