Many-body effects in momentum-space lattices*

Nonlinear interactions, when added to a tight-binding lattice system, can result in many interesting phenomena. The physics of such a lattice model can be described in terms of a bosonic Josephson junction array, allowing for the study of phenomena similar to those found in tunnel-coupled superconductors. Using a lattice made of coupled momentum states, we show measurements progressing towards the full Josephson array. By tuning the effective interaction strength, we observe the onset of self-trapping in a one-dimensional lattice, and further show collective Bloch oscillations on a tilted array.