EQuAL Seminar: Yifei Bai

"Driven 1D Quasicrystals: Localization, Critical Phases, and Topology"

Floquet engineering can be used as a tool to create exotic phases of matter, including some without any static analogue. The isolation and tunability of ultracold atoms offer a unique experimental platform to study such non-equilibrium phenomena. I will discuss recent experimental and theoretical progress in the study of periodically-driven quasicrystals. After a short introduction on the cold atom platform and Floquet systems, I will present recent experimental results on the reversible control of a localization quantum phase transition, and on the competition between dynamic and Anderson localization in 1D. I will discuss a unifying theoretical picture which elucidates the connections between these results by mapping the 1D quasicrystal to a 2D integer quantum Hall system, in which our modulation protocol maps to incident laser light with fully tunable polarization. This mapping suggests some interesting possibilities, such as Floquet-engineering a critical phase hosting multifractal eigenstates without fine-tuning, or creating a Floquet topological insulator. I will conclude with a few remarks on the impact of many-body interactions.