QM Seminar Speaker Paolo Molignini (ETH Zurich) Wednesday, January 23

Time: 2:00 pm
Venue: LeConte 402
Title: Criticality and universality of Floquet topological phase transitions

Abstract: Periodic driving has recently emerged as an extremely versatile tool to engineer and tune exotic topological states of matter in a controlled
way. For example, periodic driving generates a cascade of Majorana edge
modes beyond the static limitation of one per edge in the Kitaev chain,
resulting in a hierarchy of associated topological phase transitions
(TPT’s). Understanding the critical behavior of such out-of-equilibrium
TPT’s is therefore an important step in the quest to harness the unique
properties of Floquet systems.
In this talk, I will compare the nature of the topological phase
transitions in various static and periodically driven systems by means
of a renormalization group procedure on the curvature functions used to
construct topological invariants. I will demonstrate how this very
transparent and powerful method can identify the topological phase
boundaries and assess the nature of their criticality in terms of
universality classes. This procedure works even for topological phases
hosting anomalous edge modes, i.e. phases where the Floquet band Chern
number does not correspond to the number of edge states. Finally, I will
also show how the method can be effectively extended to explicitly
time-dependent curvature functions to capture the critical behavior as a
function of time.

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