Macroscopic superpositions and gravimetry with quantum magnetomechanics
  We utilise a magneto-mechanical levitated massive resonator in the quantum regime to prepare highly macroscopic quantum superposition states. Using these macroscopic superpositions we present a novel interferometry protocol to perform absolute gravimetry with a sensitivity that exceeds state of the art atom-interferometric and corner-cube gravimeters by a factor of 20. In addition, our scheme allows probing the gravitational field on a length scale eight orders of magnitude smaller than other methods. 
Mattias T. Johnsson, Gavin K. Brennen, and Jason Twamley
quant-ph