Percolation induced effects in 2D coined quantum walks: analytic asymptotic solutions (1401.5668v2)

Abstract: Quantum walks on graphs can model physical processes and serve as efficient tools in quantum information theory. Once we admit random variations in the connectivity of the underlying graph, we arrive at the problem of percolation, where the long-time behaviour appears untreatable with direct numerical methods. We develop novel analytic methods based on the theory of random unitary operations which help us to determine explicitly the asymptotic dynamics of quantum walks on 2D finite integer lattices with percolation. Based on this theory we find new unexpected features of percolated walks like asymptotic position inhomogeneity or special directional symmetry breaking.