Quantum spatial search in two-dimensional waveguide arrays

TL;DR

This paper demonstrates that continuous-time quantum walks can efficiently perform spatial search on a planar triangular lattice using 3D waveguide arrays, with experimental validation showing higher success probability than classical methods.

Contribution

The study provides the first experimental realization of quantum spatial search on a planar lattice using femtosecond laser-fabricated waveguide arrays.

Findings

Quantum spatial search outperforms classical search in probability of finding the marked site.

Experimental implementation confirms theoretical predictions of quantum walk efficiency.

Higher success probability achieved in early evolution time window.

Abstract

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.