Deterministic creation and detection of vortices in molecular Bose-Einstein condensates

Quantum vortices are characterized by the phase winding of the macroscopic wavefunction around the annulus. When two atoms are paired into a diatomic molecule, the phase of the molecule is expected to be double that of the atom. Past studies have indicated new types of vortex states in coupled atomic-molecular Bose-Einstein condensates (BECs). In this work, we deterministically create and manipulate vortices by translating two blue-detuned laser beams in an atomic BEC. Pairs of vortices with opposite circulation are generated by the motion of the beams with each vortex pinned to the position of the laser beam. We subsequently leave one vortex in the BEC and drag the other one out of the BEC. We detect the vorticity by interfering the BEC with a vortex with another BEC with no vortex. We also apply this technique to a Cs₂ molecular BEC containing vortices and test the prediction of phase doubling in the pairing processing.