Control of matter-wave superradiance with a high-finesse ring cavity

We experimentally investigate light scattering from a Bose-Einstein condensate which is positioned inside an optical ring cavity. With a cavity linewidth at the recoil limit, the resulting superradiant scattering behavior is strongly influenced by the cavity detuning. The experimental observations are interpreted with a quantum mean-field description and with a rate-equation model. We discuss applications in the context of quantum phase transitions, Dicke subradiance, and nonconventional superfluidity.