A study of intrinsic dielectric loss of tantalum based superconducting quantum circuits

Over the past decade, scientists have devoted tremendous efforts into improving design and fabrication of superconducting qubits, especially materials and interface for higher coherence times [1]. To realize large-scale fault-tolerant quantum computing, the quality of materials and interface of superconducting quantum devices need to be further improved to enhance the coherence times. In this talk, we present our work on thin film deposition and etching of tantalum together with film quality analysis. We studied superconducting resonators and qubits with engineered participation ratios which reveals the intrinsic dielectric loss of the tantalum films. In the end, we will present our work towards superconducting qubits based on Ta/TaOx/Ta Josephson junctions.

[1] W. D. Oliver and P. B. Welander, “Materials in superconducting quantum bits,” MRS Bull., vol. 38, no. 10, pp. 816–825, 2013.