Interface Piezoelectric Loss in Superconducting Qubits

TL;DR

This paper demonstrates that interface piezoelectricity causes dissipation in superconducting qubits on silicon, revealing a new loss mechanism that can dominate at high frequencies.

Contribution

It provides direct experimental evidence of interface piezoelectricity as a loss channel in superconducting qubits, supported by multiphysics simulations.

Findings

Observation of up to twofold reduction in qubit lifetime when resonant with mechanical modes.

Direct evidence of interface piezoelectricity as a dissipation mechanism.

Interface piezoelectric loss can surpass two-level system loss at high frequencies.

Abstract

Dissipation remains a central obstacle to improving superconducting quantum circuits, yet the microscopic origins of loss in widely used materials platforms are not fully understood. Here, we report the observation of interface piezoelectricity-induced dissipation in superconducting qubits fabricated on high-resistivity silicon. Our devices use a transmon qubit with a shunt capacitor that simultaneously serves as an interdigital transducer embedded in a surface acoustic wave resonator. By tuning the qubit transition into resonance with discrete mechanical modes, we observe up to a factor-of-two reduction in qubit lifetime, consistent with energy exchange between the qubit and mechanical modes mediated by piezoelectric coupling at the aluminum-silicon interface. Our findings provide direct evidence for interface piezoelectricity as a distinct loss channel in superconducting qubits. Combined with multiphysics simulations, these findings suggest that interface piezoelectric loss can dominate over loss from two-level systems at sufficiently high frequencies.