Imaging and Probing Atomically Thin Quantum Material Devices at the Nanoscale

Prof. Jairo Velasco
Tuesday, February 27, 2024
11:00 am
NS2 1201

Abstract: The harnessing and manipulation of electronic states in quantum materials has the potential to revolutionize computation, sensing, storage, and communications, thus impacting multiple facets of our everyday lives. In this talk I will discuss my group’s recent experiments with graphene, a highly versatile carbon-based quantum material that hosts ultra-relativistic charges. This unique attribute can be leveraged for future quantum technologies.

Specifically, I will focus on a set of experiments that utilize confinement, nanoscale visualization, and spectroscopy to reveal new properties of the ultra-relativistic states hosted by graphene-based quantum dots (QDs). In one experiment, we use the scanning tunneling microscope to corral graphene charges into circular QD structures and then subject these charges to a perpendicular magnetic field. This enables the observation of a giant orbital Zeeman splitting for trapped ultra-relativistic electrons in graphene QDs. Such splitting can be used for magnetic field sensing, information encoding, and quantum simulation. In a second experiment, we realize a graphene-based stadium shaped QD with a sharp potential profile that is compatible with scanning tunneling microscopy. This structure enables the first imaging of the highly elusive quantum scar states, which consist of an enhanced wavefunction probability density along unstable classical periodic orbits and are a signature of quantum chaos. Notably, chaotic systems are sensitive to perturbations and could lead to remarkable devices if they can be harnessed. Therefore, studying scar states provides a pathway towards this goal and potentially facilitates a new type of quantum device.

About the Speaker: 

Jairo Velasco Jr. is an Associate Professor of Physics at the University of California Santa Cruz. His research interests include the study of electronic properties and structure of two-dimensionalmaterials. He received his PhD in physics from the University of California Riverside in 2012 with Jeanie Lau. He was then a President’s Postdoctoral Fellow in Mike Crommie’s group at the University of California Berkeley from 2012-2015. Dr. Velasco is arecipient of the NSF early CAREER award (2018) and the Gordon and Betty Moore Foundation Experimental Physics Investigator Award (2022).

Luis Jauregui