Measurement of the Low-Temperature Loss Tangent of High-Resistivity Silicon Using a High- Q Superconducting Resonator

Abstract

Even though silicon is widely used in superconducting quantum processors as the substrate upon which qubits are fabricated, the effect of silicon on the performance of the qubits is not fully understood. Using ultrahigh-quality microwave cavities to measure dielectric loss with parts-per-billion precision, the authors clearly show that using silicon is detrimental to qubit coherence time. The loss tangent found here is an order of magnitude worse than previously measured. This study sheds light on the physical mechanisms behind dissipation in silicon, and highlights the need for further work to fully understand the origin of these losses, and how to mitigate them.