Abstract : Considerable progress was made during the grant period toward establishing a chip based atom interferometer. At the beginning of the gBECi period, no coherent on-chip beam splitter had been demonstrated. During the funding period, we developed two area enclosing interferometers with demonstrated coherence preservation: one using optical pulses, the other one using RF dressed potentials. Technical improvements in the moving guide technique should provide a 1cm2 enclosed area in a device with a length ~ 1 cm. We addressed in several studies the role of interactions in a Bose-Einstein condensate. This can lead to phase diffusion and phase fluctuations. We showed that a BEC interferometer can be robust against phase fluctuations, that interactions can lead to number squeezing, which slows down phase diffusion, and led to a considerable enhancement of the coherence time, and finally, that soliton-type excitations in an interacting condensate can be used to read out the phase of the interferometer after recombining the split condensate. Technical breakthroughs include improved atom chip fabrication methods, and continuous non-destructive optical readout of the interferometer phase. In related work, we demonstrated quantum reflection with normal incidence and studied it for different surfaces. Single photon sources have been developed.