There’s Plenty of Diffusion at the Bottom

The formulation of quantum mechanics in the late 1920s forever changed physics. More recently, quantum materials have emerged, offering fascinating opportunities in physical chemistry. Elementary interactions mediated by the diffusion of electrons, protons, atoms, molecules, and other quasiparticles in quantum materials give rise to intriguing phases and enable advanced technologies. However, investigating these diffusion-related phenomena at the relevant length scales requires high-resolution methods. Traditional far-field optical imaging and spectroscopy techniques are constrained by the diffraction limit of light.

Interestingly, during the same period in the late 1920s, a visionary scientist named Synge introduced a groundbreaking concept of near-field optics that could circumvent the diffraction limit. Synge shared his idea with Einstein, who encouraged him to publish it. After many years of various pioneering works by different groups, a powerful modern nano-optical technique
(scattering-type scanning near-field optical microscope), a variant of Synge’s original idea, was born.(Hillenbrand, Abate et al. 2025)

In this talk, I will present recent results that provide quantitative insights into how diffusion alters the complex dielectric function of correlated oxides and van der Waals crystals at the nanoscale. Our recent results reveal how an applied field perturbs diffusing ion distributions at the nanoscale in in these materials, leading to ordered reconfigurable phases.(Fali, Zhang et al. 2021, Gamage, Manna et al. 2024) This reconfigurability enables the design of robust artificial synapses and opens new frontiers for fundamental understanding of memory, learning, and information retention for brain-inspired information processing.(Zhang, Park et al. 2022) I will also share an exciting new direction we have been exploring on the connection between diffusion and topology, focusing on the role of path-connectivity as a topological invariant that determines whether a diffusing particle can reach a target receptor within a confined region, an idea with broad relevance across diverse physical and biological systems.( Abate, et al 2026)

Along the way, I will also show a few fun examples, including music-inspired demonstrations that highlight molecule - surface interactions, and I will conclude with a live cello piece to cap off what I hope will be an exciting talk!

Speaker: Yohannes Abate, University of Georgia