This thesis presents a theoretical investigation into the creation and exploitation of quantum
correlations and entanglement among ultracold atoms. Specifically it focuses on these
non-classical effects in two contexts: (i) tests of local realism with massive particles e.g.
violations of a Bell inequality and the EPR paradox and (ii) realization of quantum technology
by exploitation of entanglement for example quantum-enhanced metrology. In particular the
work presented in this thesis emphasizes the possibility of demonstrating and characterizing
entanglement in realistic experiments beyond the simple toy-models often discussed in the
literature. The importance and relevance of this thesis are reflected in a spate of recent
publications regarding experimental demonstrations of the atomic Hong-Ou-Mandel effect
observation of EPR entanglement with massive particles and a demonstration of an atomic SU(1 1)
interferometer. With a separate chapter on each of these systems this thesis is at the
forefront of current research in ultracold atomic physics.
