Quantum walks of correlated photon pairs in two-dimensional waveguide arrays

TL;DR

This paper demonstrates quantum walks of correlated photon pairs in a 2D waveguide array, revealing non-classical interference effects and unique correlation behaviors in a non-planar structure.

Contribution

It introduces a novel 2D waveguide network for quantum walks, showing non-classical correlations and interference in a complex, non-planar geometry.

Findings

High-visibility quantum interference observed

Strong correlation and independence of quantum walkers

Violations of classical inequalities indicating non-classical behavior

Abstract

We demonstrate quantum walks of correlated photons in a 2D network of directly laser written waveguides coupled in a 'swiss cross' arrangement. The correlated detection events show high-visibility quantum interference and unique composite behaviour: strong correlation and independence of the quantum walkers, between and within the planes of the cross. Violations of a classically defined inequality, for photons injected in the same plane and in orthogonal planes, reveal non-classical behaviour in a non-planar structure.