March 12
@
4:00 PM
–
5:00 PM
The ME 903: Graduate Student Lecture Series features campus and visiting speakers who present on a variety of research topics in the field of mechanical engineering. Professor Harley Johnson is a professor at the University of Illinois – Urbana Champaign.
Presentation Title: Defects in Quantum Materials and Perspectives on the Future of Quantum Computing
Abstract: Electronic and quantum materials, which are central to the development of devices for future applications in quantum information science, host a variety of crystalline defects that give rise to interesting properties. In order to harness these properties for new applications, it is necessary to understand the mechanics and physics of the defects and their interactions.
In this talk, I will first present results on defects in layered two-dimensional materials, including dislocations either in-plane or out-of-plane with respect to the 2D layered structure. Recently, twisted multilayer 2D material structures have been of interest due to the presence of flat bands and other emergent properties — including unconventional superconductivity — associated with moiré superlattices. Periodic regions of crystalline commensurability making up these superlattices are now understood to be separated by interlayer dislocations, with Burgers vectors and line directions in the plane of the 2D material, and having either edge or screw character. Using density functional theory and quantum Monte Carlo-fitted total energy tight-binding calculations, I show that out-of-plane relaxation of the structures makes possible unique helical dislocations in bilayer graphene, and that the presence of these helical dislocation lines coincides precisely with the so-called magic-angle condition at which unconventional superconductivity is observed. I then describe a different dislocation structure, with line direction oriented out-of-plane, but which also has a helical structure. Such a screw dislocation, which adopts a double-helix dislocation core configuration in bilayer structures, is expected to create conditions for exotic transport properties in certain classes of layered topological insulator materials.
I will then take a broader perspective and briefly describe some major efforts to scale up quantum applications, focusing on an historic new public-private partnership developing in Chicago – the Illinois Quantum and Microelectronics Park. This effort will be discussed in the context of university, national lab, and industry partnerships across the region, with a goal of describing opportunities for engagement and targets for the scale-up of quantum computing hardware and algorithms over the next 5-10 years.
Bio: Harley T. Johnson is a Founder Professor in Mechanical Science and Engineering at the University of Illinois Urbana-Champaign, where he has been a member of the faculty since 2001. He is the Executive Director and CEO of the Illinois Quantum and Microelectronics Park, a $1B+ public-private partnership dedicated to scale-up of quantum computing, located on 128 acres of the former US Steel Southworks site in Chicago. From 2019-2024 he served as the Associate Dean for Research in The Grainger College of Engineering, a role in which he oversaw and supported the $320M annual research portfolio in Engineering at UIUC. In this position he supported faculty research, led corporate relations, and oversaw all major engineering partnerships with the federal funding agencies.
Johnson’s research focuses on electronic and quantum materials, addressing the role of defects and deformation in their functional properties. He served as PI and Director of the Illinois Materials Research Science and Engineering Center (I-MRSEC), an $18M NSF center (2023-2029) focused on fundamental research in electronic, ionic, and quantum materials. In 2019 he founded the NSF “DIGI-MAT” Center on Materials and Data Science, based in UIUC’s National Center for Supercomputing Applications (NCSA). He has received the NSF CAREER Award, the ASME Thomas J. R. Hughes Young Investigator Award, and is a former Fulbright US Scholar. Johnson has received numerous recognitions for his teaching, and campus awards for his leadership in diversity, and for outstanding faculty leadership. In 2021 he received the University of Illinois Presidential Medallion for his leadership efforts during the Covid-19 pandemic. He is a Fellow of ASME and a Fellow of the Society of Engineering Science (SES). He received his graduate degrees from Brown University, and his undergraduate degree from Georgia Tech.