Matter-wave interference with molecular superfluids

In this work, we investigate the phase transformation from atomic to molecular Bose-Einstein condensates (BEC). Coupling between atoms and diatomic molecules can be expressed in the interaction Hamiltonian as a combination of annihilation and creation operators where we annihilate a molecule to create two atoms and vice versa. If we include the phase of the atomic and molecular wavefunctions into the interaction, the system will remain invariant as long as the phase of the molecular wavefunction is twice as that of the atomic wavefunction. To probe this phase doubling, we implement an interferometric technique utilizing vortices. Quantum vortices are characterized by the phase winding of the macroscopic wavefunction around the annulus. The phase of the vortex is doubled when we convert an atomic BEC containing a single vortex into a molecular one. To detect this phase transformation, we perform interferometry using an optical lattice to create interference fringes. The vorticity will affect the formation of interference fringes. We will report on our current progress.