Magnetic properties of chromium dipolar condensates
In this seminar, I will describe an experiment where magnetic atoms in different sites of a 3D optical lattice undergo spin-exchange processes due to long-range dipole-dipole interactions.
A Bose-Einstein condensate of Chromium atoms is loaded into deep 3D optical lattices. Due to their large magnetic dipole moment, Chromium atoms interact at long distance via dipole-dipole interactions. These interactions provide intersite spin-spin interactions without relying on super-exchange energies, which constitutes a great interest for the study of spin lattice models. In our experiment, we observe a non-equilibrium spinor dynamics resulting from inter-site Heisenberg-like spin-spin interactions provided by non-local dipole-dipole interactions. Our experiment thus reveals the interest of chromium lattice gases for the study of quantum magnetism of high-spin systems.
I will also show that the anisotropy of dipolar interactions introduces the possibility of magnetization-changing collisions. In a lattice, these collisions may resonantly happen when the energy released in a dipolar relaxation event (the Larmor energy, tuned by the magnetic field) matches the energy for band excitation. Dipolar interactions thus introduce an intrinsic non-linear spin-orbit coupling which may qualitatively modify the study of quantum magnetism.
Host: Trey Porter