Investigating microwave loss of SiGe using superconducting transmon qubits

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