  Hitting the exit node from the entrance node faster on a graph is one of the
properties that quantum walk algorithms can take advantage of to outperform
classical random walk algorithms. Especially, continuous-time quantum walks on
central-random glued binary trees have been investigated in theories
extensively for their exponentially faster hitting speed over classical random
walks. Here, using heralded single photons to represent quantum walkers and
waveguide arrays written by femtosecond laser to simulate the theoretical
graph, we are able to demonstrate the hitting efficiency of quantum walks with
tree depth as high as 16 layers for the first time. Furthermore, we expand the
graph's branching rate from 2 to 5, revealing that quantum walks exhibit more
superiority over classical random walks as branching rate increases. Our
results may shed light on the physical implementation of quantum walk
algorithms as well as quantum computation and quantum simulation.
