Abstract: We observe matter wave interference which is driven by interactions. When a BEC in a lattice potential undergoes Bloch oscillations at non-zero scattering length, the condensate quickly de-phases and develops an interference pattern inside the first Brillouin zone. The de-phasing is coherent and can be controlled and reversed by applying a suitable external potential. When tuning the scattering length to zero, de-phasing is suppressed and we can follow more than 20000 oscillations over 12 s.
We also demonstrate STIRAP transfer of Feshbach molecules produced from a BEC into the v=73 vibrational level of the singlet potential, a state with 30 THz binding energy. The transfer efficiency is 80%. Our results show that a BEC of ro-vibrational ground state molecules is within reach. |
