Quantum walks of correlated particles

TL;DR

This paper demonstrates quantum walks of two correlated photons in a waveguide array, revealing quantum correlations that surpass classical limits and enabling larger state space encoding for quantum information processing.

Contribution

First experimental realization of two-photon quantum walks in a large waveguide array, showing quantum correlations depend on input states and surpass classical bounds.

Findings

Quantum correlations violate classical limits by 76 standard deviations.

Quantum walk behavior depends critically on input photon states.

Potential for encoding information in exponentially larger quantum states.

Abstract

Quantum walks of correlated particles offer the possibility to study large-scale quantum interference, simulate biological, chemical and physical systems, and a route to universal quantum computation. Here we demonstrate quantum walks of two identical photons in an array of 21 continuously evanescently-coupled waveguides in a SiOxNy chip. We observe quantum correlations, violating a classical limit by 76 standard deviations, and find that they depend critically on the input state of the quantum walk. These results open the way to a powerful approach to quantum walks using correlated particles to encode information in an exponentially larger state space.