Henry, R.Quach, J.Su, C.-H.Greentree, A.Martin, A.2018-10-162018-10-162014Physical Review A: Atomic, Molecular and Optical Physics, 2014; 90(4):043639-1-043639-51050-29471094-1622http://hdl.handle.net/2440/115110Published 31 October 2014Ultracold atoms in optical lattices provide a unique opportunity to study Bose-Hubbard physics. In this work we show that by considering a spatially varying on-site interaction it is possible to manipulate the motion of excitations above theMott phase in a Bose-Hubbard system. Specifically, we show that it is possible to “engineer” regimes where excitations will negatively refract, facilitating the construction of a flat lens.en©2014 American Physical SocietyJournal article003009859710.1103/PhysRevA.90.0436392-s2.0-84909954734439258Quach, J. [0000-0002-3619-2505]