Coherent Reactions and Dynamics in Cs2 Molecular Quantum Gas

We report progress in our studies of ultracold cesium molecular quantum gases. Starting from an atomic Bose–Einstein condensate (BEC), we produce a molecular BEC by ramping the magnetic field across a narrow Feshbach resonance at 19.849 G. Near the resonance, we observe Bose-enhanced many-body chemical reaction dynamics in the quantum-degenerate regime. We also observe a key signature of coherent production of molecular matter-waves from atomic waves: phase doubling, in which the molecular condensate phase is precisely twice the atomic condensate phase under the atom-to-molecule conversion.

Building on this platform, we are exploring several new directions. First, we investigate the creation and trapping of Cs2 Feshbach molecules in a two-dimensional optical lattice. By isolating molecules in individual sites to suppress inelastic loss, we extend their lifetime from tens of milliseconds in a harmonic trap to beyond four seconds. Second, we study the instability of a pure molecular superfluid near the atomic Feshbach resonance.

Finally, we present an ongoing upgrade to our optical toolbox utilizing a broadband laser–illuminated digital micromirror device (DMD). This system is designed to generate uniform, programmable optical potentials with arbitrary patterns.