Coupling GaAs quantum devices to surface acoustic wave phonons

One of the challenges of quantum computing is achieving a quantum bus for long distance coupling of qubits as needed for scaling. Superconducting resonators have recently attracted attention but require operation well below the critical temperature, and are typically incompatible with magnetic fields, making integration with some qubits such as spins challenging. In contrast, Surface Acoustic Wave (SAW) resonators are realized by trapping a phonon in a cavity. They can operate in strong magnetic fields and up to high temperatures without significant loss of quality. Further. SAW resonators with quality factors exceeding 20,000 at cryogenic temperatures have been shown.

GaAs heterostructures offer high mobility 2D electron gases (2DEGs) for quantum dot and quantum Hall experiments. In addition, GaAs is a piezoelectric material, allowing fabrication of SAW resonators using lithography techniques. We present SAW resonators in the GHz frequency range integrated with a 2DEG and study the interactions between SAWs and other structures such as quantum dots and Hall bars, working towards charge- and/or spin-phonon coupling.

In the future, this could be implemented on other non-piezoelectric substrates such as Si using thin piezoelectric films for highly scalable qubit networks.