Near-field THz spectroscopy of tantalum films for superconducting quantum devices

Superconducting quantum circuits are one of the leading quantum computing platforms. To advance superconducting quantum computing to a point of practical importance, it is critical to identify and address material imperfections that lead to decoherence. In this talk, I will show how terahertz Scanning Near-field Optical Microscopy (SNOM) can be used to probe functional devices such as coplanar microwave resonators and inform the processing of new materials for quantum technology. I will discuss the recent observation of a localized vibrational excess on the surface of tantalum films and how this excess is connected to the boson peak, a universal signature of amorphous materials. The nanoscale identification and localization of amorphous oxides provides critical insight as amorphous materials host tunneling two level systems (TLS) – the major performance limiting factor in superconducting quantum devices.