Measuring Energy difference forces by BEC Interferometry on a Chip

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F. Baumgärtner, R. J. Sewell, S. Eriksson, I. Llorente-Garcia, Jos Dingjan, J. P. Cotter, E. A. Hinds


Phys. Rev. Lett. 105 243003 (2010)

We investigate the use of a Bose-Einstein condensate trapped on an atom chip for making interferometric measurements of small forces. A fundamental limit on sensitivity is imposed by the noise in the energy difference of the split condensates, which we measure and explain. We also consider systematic errors. A leading effect is the variation of rf magnetic field in the trap with distance from the wires on the chip surface. This can produce energy differences that are comparable with those due to gravity. We use our interferometer to weigh the (^{87})Rb atom as a proof that BEC atom chips can be used to measure small forces.