Collective Dynamical Fermi Suppression of Optically Induced Inelastic Scattering.

We observe strong dynamical suppression of optically induced loss in a weakly interacting Fermi gas as the s-wave scattering length is increased. A single trapped cigar-shaped cloud behaves as a large spin lattice in energy space with a tunable Heisenberg Hamiltonian. The loss suppression occurs as the lattice transitions into a magnetized state, where the fermionic nature of the atoms inhibits interactions. The data are quantitatively explained by incorporating spin-dependent loss into a quasiclassical collective spin vector model, the success of which enables the application of optical control of effective long-range interactions to this system.