Multimode Strong Coupling in Superconducting Cavity Piezoelectromechanics.
High-frequency mechanical resonators subjected to low thermal phonon occupancy are easier to be prepared to the ground state by direct cryogenic cooling. Their extreme stiffness, however, poses a significant challenge for external interrogations. Here we demonstrate a superconducting cavity piezoelectromechanical system in which multiple modes of a bulk acoustic resonator oscillating at 10 GHz are coupled to a planar microwave superconducting resonator with a cooperativity exceeding 2×10^{3}, deep in the strong coupling regime. By implementation of the noncontact coupling scheme to reduce mechanical dissipation, the system exhibits excellent coherence characterized by a frequency-quality-factor product of 7.5×10^{15}  Hz. Interesting dynamics of classical temporal oscillations of the microwave energy is observed, implying the coherent conversion between phonons and photons. The demonstrated high-frequency cavity piezoelectromechanics is compatible with superconducting qubits, representing an important step towards hybrid quantum systems.
Department of Electrical Engineering, Yale University, New Haven, Connecticut 06511, USA.
Xu
X
Han
Department of Electrical Engineering, Yale University, New Haven, Connecticut 06511, USA.
Chang-Ling
CL
Zou
Department of Electrical Engineering, Yale University, New Haven, Connecticut 06511, USA.
Hong X
HX
Tang