Cs Trilobite Molecules and Rydberg atom Interactions

We present results on our Cs ultracold Rydberg atom experiments involving trilobite molecules and Rydberg atom interactions. Trilobite molecules are predicted to have giant, body-fixed permanent dipole moments ($\sim 1 $kD). We present measurements of the Stark shifts of the trilobite states in Cs due to the application of a constant external electric field. We also will present progress on studies of anisotropic interactions between pairs of Rydberg atoms. We will focus on angular-dependent S-matrix calculations of collisions between 89D+89D Rydberg atom pairs in a 100 mV/cm electric field. In this field, the dipole-dipole interaction dominates over the van-der-Waals interaction, creating a large anisotropy in the potential surfaces.