Entanglement by Path Identity

TL;DR

This paper introduces a new method for creating complex quantum entanglement using superposition and path alignment of photons, enabling high-dimensional and multipartite entanglement from non-entangled pairs.

Contribution

The paper presents a novel technique for generating multipartite and high-dimensional entanglement through path identity, inspired by computer algorithm analysis.

Findings

High-dimensional entanglement can be generated from non-entangled photon pairs.

The method is experimentally feasible for various classes of multiphoton entanglement.

Computer algorithms can inspire new quantum experimental techniques.

Abstract

Quantum entanglement is one of the most prominent features of quantum mechanics and forms the basis of quantum information technologies. Here we present a novel method for the creation of quantum entanglement in multipartite and high-dimensional systems. The two ingredients are 1) superposition of photon pairs with different origins and 2) aligning photons such that their paths are identical. We explain the experimentally feasible creation of various classes of multiphoton entanglement encoded in polarization as well as in high-dimensional Hilbert spaces -- starting only from non-entangled photon pairs. For two photons, arbitrary high-dimensional entanglement can be created. The idea of generating entanglement by path identity could also apply to other quantum entities than photons. We discovered the technique by analyzing the output of a computer algorithm. This shows that computer designed quantum experiments can be inspirations for new techniques.