title: Precise determination of the structure factor and contact in a unitary Fermi gas.
abstract: We present a high-precision determination of the universal contact parameter in a strongly interacting Fermi gas. In a trapped gas at unitarity, we find the contact to be 3.06±0.08 at a temperature of 0.08 of the Fermi temperature in a harmonic trap. The contact governs the high-momentum (short-range) properties of these systems, and this low-temperature measurement provides a new benchmark for the zero-temperature homogeneous contact. The experimental measurement utilizes Bragg spectroscopy to obtain the dynamic and static structure factors of ultracold Fermi gases at high momentum in the unitarity and molecular Bose-Einstein condensate regimes. We have also performed quantum Monte Carlo calculations of the static properties, extending from the weakly coupled BCS regime to the strongly coupled Bose-Einstein condensate case, that show agreement with experiment at the level of a few percent.
authors: Centre for Atom Optics and Ultrafast Spectroscopy, Swinburne University of Technology, Melbourne, Victoria 3122, Australia.
authors: Sascha
authors: S
authors: Hoinka
authors: Marcus
authors: M
authors: Lingham
authors: Kristian
authors: K
authors: Fenech
authors: Hui
authors: H
authors: Hu
authors: Chris J
authors: CJ
authors: Vale
authors: Joaquín E
authors: JE
authors: Drut
authors: Stefano
authors: S
authors: Gandolfi