Special CPM Seminar

Thermometry and Cooling of Ultracold Atoms in Spin-Dependent Optical Lattices

David McKay

University of Toronto / University of Illinois

Atoms in a spin-dependant optical lattice »

Schematic of atoms in a spin-dependent optical lattice — blue atoms (m_F=-1 state of ⁸⁷Rb) experience a lattice potential and are immersed in a bath of red atoms (m_F=0 state of ⁸⁷Rb) which do not experience a lattice. To detect the atoms we release and image after expansion (bottom). The lattice potential causes the Bose-condensed cloud of blue atoms to diffract.

Ultracold atoms in optical lattices have emerged as an ideal realization of Hubbard models, which are paradigms of strongly correlated quantum matter. However, our ability to study interesting phases (e.g., quantum magnetism) is currently limited by our failure to access and to measure sufficiently low temperatures. In this talk I will discuss our work at the University of Illinois towards solving these issues using a new tool — a fully three-dimensional spin-dependent optical lattice. In particular, this setup enables us to realize a strongly correlated lattice system immersed in a bath of weakly interacting free atoms. I will present recent measurements studying thermalization between these two systems, and I will comment on work towards implementing cooling by selectively driving atoms into higher lattice bands.