Discrete Feynman propagator for the Weyl quantum walk in 2+1 dimensions
  Recently quantum walks have been considered as a possible fundamental description of the dynamics of relativistic quantum fields. Within this scenario we derive the analytical solution of the Weyl walk in 2+1 dimensions. We present a discrete path-integral formulation of the Feynman propagator based on the binary encoding of paths on the lattice. The derivation exploits a special feature of the Weyl walk, that occurs also in other dimensions, that is closure under multiplication of the set of the walk transition matrices. This result opens the perspective of a similar solution in the 3+1 case. 
G. M. D'Ariano, N. Mosco, P. Perinotti and A. Tosini
quant-ph hep-lat math-ph math.MP