Weak force detection using a double Bose-Einstein condensate
  A Bose-Einstein condensate may be used to make precise measurements of weak forces, utilizing the macroscopic occupation of a single quantum state. We present a scheme which uses a condensate in a double well potential to do this. The required initial state of the condensate is discussed, and the limitations on the sensitivity due to atom collisions and external coupling are analyzed. 
J. F. Corney, G. J. Milburn and Weiping Zhang