Tunable magnetic alignment between trapped exciton-polariton condensates
  Tunable spin correlations are found to arise between two neighboring trapped exciton-polariton condensates which spin-polarize spontaneously. We observe a crossover from an antiferromagnetic- to a ferromagnetic pair state by reducing the coupling barrier in real-time using control of the imprinted pattern of pump light. Fast optical switching of both condensates is then achieved by resonantly but weakly triggering only a single condensate. These effects can be explained as the competition between spin bifurcations and spin-preserving Josephson coupling between the two condensates, and open the way to polariton Bose-Hubbard ladders. 
H. Ohadi, Y. del Valle-Inclan Redondo, A. Dreismann, Y. G. Rubo, F.   Pinsker, S. I. Tsintzos, Z. Hatzopoulos, P. G. Savvidi...
cond-mat.other