Investigating microwave loss of SiGe using superconducting transmon qubits

TL;DR

This study fabricates transmon qubits on SiGe layers and investigates their microwave loss properties at cryogenic temperatures, demonstrating high quality factors suitable for quantum computing applications.

Contribution

It introduces a method for integrating SiGe with superconducting qubits and evaluates their microwave loss characteristics at cryogenic temperatures.

Findings

Relaxation times up to 100 μs

Quality factor Q above 4 million

Compatibility of SiGe/Si heterostructures with quantum circuits

Abstract

Silicon-Germanium (SiGe) is a material that possesses a multitude of applications ranging from transistors to eletro-optical modulators and quantum dots. The diverse properties of SiGe also make it attractive to implementations involving superconducting quantum computing. Here we demonstrate the fabrication of transmon quantum bits on SiGe layers and investigate the microwave loss properties of SiGe at cryogenic temperatures and single photon microwave powers. We find relaxation times of up to 100 $\mu$s, corresponding to a quality factor Q above 4 M for large pad transmons. The high Q values obtained indicate that the SiGe/Si heterostructure is compatible with state of the art performance of superconducting quantum circuits.