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Contact Measurements on a Strongly Interacting Bose Gas

TitleContact Measurements on a Strongly Interacting Bose Gas
Publication TypeThesis
Year of Publication2012
AuthorsWild, RJ
Abstract

A powerful set of universal relations, centered on a quantity called the contact, connects the strength of short-range two-body correlations to the thermodynamics of a many-body system with delta-function interactions. For bosons, the fact that contact spectroscopy can be used to probe the gas on short timescales is potentially useful given the decreasing stability of BECs with increasing interactions. Successfully measuring the contact requires careful control of experimental parameters such as the magnetic field and the RF probe pulse. In this thesis I report on measurements of the contact, using RF spectroscopy, for an 85Rb atomic Bose-Einstein condensate (BEC). The measured contact exhibits beyond-mean-field behavior, the degree of which is dependent on the rates of change of the scattering length. A potential complication is the added possibility, for bosons, of three-body interactions. In investigating this issue, we have located an Efimov resonance for 85Rb atoms with loss measurements and thus determined the three-body interaction parameter.