Physics (Internal)

Observation of Bose-Einstein Condensation in the Harper-Hofstadter Hamiltonian

This event is part of the Condensed Matter Theory Seminar Series.

Extensions of Berry’s phase and the quantum Hall effect have led to the discovery of new states of matter with topological properties. Traditionally, this has been achieved using magnetic fields or spin–orbit interactions, which couple only to charged particles. For neutral ultracold atoms, synthetic magnetic fields have been created that are strong enough to realize the Harper–Hofstadter model. In this talk, I report on work creating and studying Bose–Einstein condensation in the Harper–Hofstadter Hamiltonian with one-half flux quantum per lattice unit cell. The diffraction pattern of the superfluid state directly shows the momentum distribution of the wavefunction, which is gauge-dependent, and it reveals both the reduced symmetry of the vector potential and the twofold degeneracy of the ground state. I present an adiabatic many-body state preparation protocol via the Mott insulating phase and show the superfluid ground state in a three-dimensional lattice with strong interactions. Future prospects for exploring exotic states close to the Mott transition are discussed in addition to the prospects of creating cold-atom topological insulators by introducing the spin degree of freedom.