Interacting atoms under strong quantum confinement - art. no. 063416

We calculate the energy-level shifts of a tightly confined trapped alkali-m etal atom in the presence of a second trapped atom. A complete microscopic description of the interaction energy between the two atoms is used. This a llows us to study tightly confined atoms near a Feshbach resonance and to e valuate the usefulness of the regularized delta-function potential approxim ation. We present results for sodium and cesium when confined in a spherica lly symmetric harmonic optical trap. Possible implications of the level shi fts and collisional decoherence for quantum computing with atomic systems a re given.