An SPT without "S" via quasiperiodic driving

Event Dates: 

Wednesday, October 28, 2020 - 12:00pm

CTQM Seminar Type: 

  • CTQM Discussion

Seminar Location: 

  • Other

Seminar Location Other:

Speaker Name(s): 

Aaron Friedman

Speaker Affiliation(s): 

CU Boulder

Abstract, Event Details: 

We construct an example of a 1d quasiperiodically driven spin chain whose edge states can coherently store quantum information, protected by a combination of localization, dynamics, and topology. Unlike analogous behavior in static and periodically driven (Floquet) spin chains, this model does not rely upon microscopic symmetry protection: Instead, the edge states are protected purely by emergent dynamical symmetries. We explore the dynamical signatures of this Emergent Dynamical Symmetry-Protected Topological (EDSPT) order through exact numerics, time evolving block decimation, and analytic high-frequency expansion, finding evidence that the EDSPT is a stable dynamical phase protected by bulk many-body localization up to (at least) stretched-exponentially long time scales, and possibly beyond. We argue that EDSPTs are special to the quasiperiodically driven setting, and cannot arise in Floquet systems. Moreover, we find evidence of a new type of boundary criticality, in which the edge spin dynamics transition from quasiperiodic to chaotic, leading to bulk thermalization.

Research Category: