MSE Seminar: Chris Richardson (Maryland)
Epitaxial nitride thin films for superconducting quantum circuits
Engineered superconducting thin film heterostructures are needed to create future generations of high-fidelity superconducting qubits. Through a structure-first approach, Plasma Assisted Molecular Beam Epitaxy (PAMBE) is used to grow superconducting niobium titanium nitride alloys (NbxTi1-xN) and wide band gap aluminum nitride on sapphire wafers. Alloyed thin films, with an engineered lattice constant, are designed and synthesized to match the in-plane atomic spacing of AlN. Annealed thin films are grown at temperatures below 1000 oC, exhibit a superconducting critical temperature over 16 K, and a root-mean-square surface roughness less than 1 Å. They are made into superconducting resonators with high quality factors at low powers, non-saturating loss at high powers, and low kinetic inductance. These engineered superconducting thin films are ideal for the creation of an epitaxial Josephson junction and qubit devices that operate at higher temperatures.
Bio: Chris Richardson is the director of the Laboratory for Physical Sciences Qubit Collaboratory (one of 13 National Quantum Information Science Research Centers supporting the National Quantum Initiative), a research scientist at LPS, and an adjunct professor in the Department of Materials Science and Engineering at the University of Maryland. He is also co-chair of the White House Office of Science and Technology Policy, National Quantum Coordination Office, Interdepartmental Working Group On Workforce Development that produced the Quantum information Science and Technology Workforce Development National Strategic Plan. He received his B.S. degree in engineering physics from the University of Maine, and M.S. and Ph.D. degrees in materials science and engineering from Johns Hopkins University. He has authored papers and conference contributions in technical areas spanning epitaxial material design, thin film growth, materials characterization, optoelectronic devices, and superconductor resonators. Richardson’s current research interests include molecular beam epitaxy of dissimilar materials and the materials science of quantum information systems.
