Performance of a nonlinear atom interferometer integrated on a chip

We study the dynamics of Bose-Einstein condensates in time-dependent microtraps in view of applications in atom interferometry. The scheme is based on the slow splitting and recombination of an elongated harmonic trap. It is shown that the nonlinearity due to the mean field atom-atom interaction increases the sensitivity of the interferometers to an applied phase shift. This feature is connected with the adiabatic generation of a dark soliton. The soliton typically oscillates in the recombined trap, and its amplitude provides an alternative readout of the interferometer phase. We analyse the robustness of this phenomenon with respect to thermal fluctuations, due to (i) initially excited Bogoliubov modes and (ii) magnetic near fields in an electromagnetic surface trap.