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Magnetic properties of chromium dipolar condensates

April 21, 2014 - 11:00am
Bruno Laburthe-Tolra
Laboratoire de Physique des Lasers – Paris 13 University & CNRS – UMR 7538

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

CSS 2400
College Park, MD 20742