Figure 6
From: Quantum random walks on congested lattices and the effect of dephasing
The variance σ2 and escape probability 
obtained at the final time step plotted against the congestion probability 1−
for varying values of the dephasing probability pd on a square two-dimensional lattice of size given by tmax = 75.
(a) The propagation of the walker decreases monotonically with the congestion rate for increasing values of dephasing 
. A quadratic behavior remains for small values of 
. (b) The escape boundary is at 
. With decreasing 
the quantum walker has a larger chance to escape the boundary. As 
increases the QRW enters the classical regime and quantum advantages are lost.
