Anderson localization of entangled photons in an integrated quantum walk

TL;DR

This paper demonstrates the first experimental observation of Anderson localization of entangled photon pairs in a disordered quantum walk setup, revealing how wave-function symmetry influences localization.

Contribution

It introduces a novel integrated photonic platform to observe Anderson localization of entangled photons, exploring the effects of disorder and particle statistics without interactions.

Findings

Localization depends on disorder type and wave-function symmetry

Entangled photons exhibit different localization behaviors based on bosonic or fermionic statistics

The integrated interferometer array enables controlled studies of quantum walk dynamics

Abstract

Waves fail to propagate in random media. First predicted for quantum particles in the presence of a disordered potential, Anderson localization has been observed also in classical acoustics, electromagnetism and optics. Here, for the first time, we report the observation of Anderson localization of pairs of entangled photons in a two-particle discrete quantum walk affected by position dependent disorder. A quantum walk on a disordered lattice is realized by an integrated array of interferometers fabricated in glass by femtosecond laser writing. A novel technique is used to introduce a controlled phase shift into each unit mesh of the network. Polarization entanglement is exploited to simulate the different symmetries of the two-walker system. We are thus able to experimentally investigate the genuine effect of (bosonic and fermionic) statistics in the absence of interaction between the particles. We will show how different types of randomness and the symmetry of the wave-function affect the localization of the entangled walkers.