QG Seminar: Flat band physics: The Carrollian way (Aritra Banerjee, Birla Institute of Technology and Science)

QG Seminar

Speaker: Aritra Banerjee (Birla Institute of Technology and Science)

Title: Flat band physics: The Carrollian way

Abstract:

The Carroll group becomes important while describing symmetries on null hypersurfaces and can be associated with an ultra-relativistic or ultra-local limit, where a characteristic velocity of the system goes to zero. Our work shows how these structures make Carrollian symmetries indispensable in the construction of dispersionless fermionic lattice systems with all flat-band spectra from first principles. The key ingredient of this construction is the identification of Compact Localised States (CLSs), which appear naturally by demanding the so-called supertranslation invariance for the system.