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Making "Contact" with Ultracold Atom Experiments

Ultracold atoms are often praised for the high degree to which they can be controlled and manipulated to resemble complex many-body systems that occur in nature. The power in using ultracold atoms to simulate their messy condensed matter physics counterparts is, in part, due to the the close connection between experiment and theory. In this talk, I will introduce a quantity that can be used to benchmark theoretical treatments of an ultracold atomic gas called the contact . The contact is centre stage in a set of universal relations that relate microscopic properties of the gas and macroscopic thermodynamics. Once the contact is measured or calculated researchers have immediate access, for instance, to the pair-correlation function, the high-energy tail of the momentum distribution, and the free energy of the system. I will present recent measurements of the contact for an ultracold Fermi gas and show new results that point toward extensions of the contact formalism.