Loop Quantization of a Model for D=1+2 (Anti)de Sitter Gravity Coupled   to Topological Matter
  We present a complete quantization of Lorentzian D=1+2 gravity with cosmological constant, coupled to a set of topological matter fields. The approach of Loop Quantum Gravity is used thanks to a partial gauge fixing leaving a residual gauge invariance under a compact semi-simple gauge group, namely Spin(4) = SU(2) x SU(2). A pair of quantum observables is constructed, which are non-trivial despite of being null at the classical level. 
Clisthenis P. Constantinidis, Zui Oporto and Olivier Piguet
gr-qc