Integer quantum Hall effect for bosons: A physical realization
  A simple physical realization of an integer quantum Hall state of interacting two dimensional bosons is provided. This is an example of a "symmetry-protected topological" (SPT) phase which is a generalization of the concept of topological insulators to systems of interacting bosons or fermions. Universal physical properties of the boson integer quantum Hall state are described and shown to correspond to those expected from general classifications of SPT phases. 
T. Senthil, Michael Levin
cond-mat.str-el cond-mat.quant-gas