Creation and detection of a mesoscopic gas in a non-local quantum   superposition
  We investigate the scattering of a quantum matter wave soliton on a barrier in a one dimensional geometry and we show that it can lead to mesoscopic Schr\"odinger cat states, where the atomic gas is in a coherent superposition of being in the half-space to the left of the barrier and being in the half-space to the right of the barrier. We propose an interferometric method to reveal the coherent nature of this superposition and we discuss in details the experimental feasibility. 
Christoph Weiss (LKB - Lhomond), Yvan Castin (LKB - Lhomond)