# Colloquia

**Attend virtually via Zoom:**##### https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp

Friday, December 3, 2021

3:30 PM

Physics Building, Room 204

## "Floquet-engineering topological Dirac bands in an optical lattice"

**Ian Spielman , NIST and The University of Maryland**

[Host: Prof. Dima Pesin]

Over the years my group has performed a number of experiments realizing relativistic physics using cold atoms — described by the 1D Dirac Hamiltonian in some degree of approximation. I will begin by reviewing these results in conjunction with those from the whole of the cold-atom community.

With that backdrop, I describe a spin dependent bipartite Floquet lattice, in which the dispersion relation is linear for all points in the Brillouin zone. The (stroboscopic) Floquet spectrum of our periodically-driven Hamiltonian features perfect spin-momentum locking, and a linear Dirac dispersion. These bands are protected by a Floquet topological invariant which we directly measure by using quantum state tomography.

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