Piezoelectrically Coupling a Traveling-Wave Phononic Cavity to a Transmon Qubit

Quantum acoustic devices as quantum transducers show great potential in hybrid quantum processors, especially due to their ability to convert quantum information from microwave and optical carriers into propagating phonons. In this talk, we describe a circuit quantum acoustodynamics system, consisting of a traveling-wave phononic cavity based on Lithium Niobate on a sapphire substrate coupled with a transmon qubit. The phononic cavity has a high intrinsic quality and is also highly scalable. We apply two time-domain filtering methods to post-process the transmission spectrum of the phononic cavity and distinguish the Rayleigh-like and Love-like modes. The phononic cavity exhibits rich multi-mode dynamics when coupling to a qubit and provides a novel platform for quantum computing and quantum information processing.