  Continuous-time quantum walks (CTQW) have shown the capability to perform
efficiently the spatial search of a marked site on many kinds of graphs.
However, most of such graphs are hard to realize in an experimental setting.
Here we study CTQW spatial search on a planar triangular lattice by means of
both numerical simulations and experiments. The experiments are performed using
three-dimensional waveguide arrays fabricated by femtosecond laser pulses,
illuminated by coherent light. We show that the retrieval of the marked site by
the quantum walker is accomplished with higher probability than the classical
counterpart, in a convenient time window placed early in the evolution.
