Proposal for the Creation and Optical Detection of Spin Cat States in   Bose-Einstein Condensates
  We propose a method to create "spin cat states", i.e. macroscopic superpositions of coherent spin states, in Bose-Einstein condensates using the Kerr nonlinearity due to atomic collisions. Based on a detailed study of atom loss, we conclude that cat sizes of hundreds of atoms should be realistic. The existence of the spin cat states can be demonstrated by optical readout. Our analysis also includes the effects of higher-order nonlinearities, atom number fluctuations, and limited readout efficiency. 
Hon Wai Lau, Zachary Dutton, Tian Wang, Christoph Simon
quant-ph cond-mat.quant-gas physics.atom-ph