In order to resolve the apparent implications from quantum mechanics that "action at a distance" is possible, a number of local-hidden variable interpretations of quantum mechanics were proposed. These theories postulated there is a more fundamental theory underling quantum mechanics, that obeys the principle of "local realism", which is that objects can only be influenced by there immediate surroundings. In 1964 Bell proposed his famous Bell inequality, which is a set of conditions that all possible local-hidden-variable theories must obey. Over the previous decades a large number of experimental investigations have been conducted which refute many descriptions of local-hidden variable theories. However, no Bell violation has been conducted with massive particles using external degrees of freedom, such as momentum. This would be a vital step forward scientifically, as it would be a milestone in quantum atom optics, and the scaling of such a Bell violation has implications in the study of quantum gravity.

In this seminar, I will present our experimental measurment of a highly forbidden atomic transition in helium, as well as the experimental techniques we are developing in order to perform a  Bell's inequality violation using momentum correlated atoms. We will first dicuss how we are utalising s-wave scattering halos, formed by colliding Bose-Einstein Condensates, as a reliable source of momentum entangled atoms. We will then cover our implementation of Bragg diffraction as the basis of our atomic interferometer. Finally we will show the results of our atomic interferometer so far.