Topological protection versus degree of entanglement of two-photon light in photonic topological insulators

Demetrios N. Christodoulides,Armando Perez-Leija,Miguel A. Bandres,Konrad Tschernig,Kurt Busch,Álvaro Jimenez-Galán,Misha Ivanov

doi:10.1038/s41467-021-22264-3

Demetrios N. Christodoulides, Armando Perez-Leija + Show 5 more

Open Access

https://doi.org/10.1038/s41467-021-22264-3

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Abstract

Topological insulators combine insulating properties in the bulk with scattering-free transport along edges, supporting dissipationless unidirectional energy and information flow even in the presence of defects and disorder. The feasibility of engineering quantum Hamiltonians with photonic tools, combined with the availability of entangled photons, raises the intriguing possibility of employing topologically protected entangled states in optical quantum computing and information processing. However, while two-photon states built as a product of two topologically protected single-photon states inherit full protection from their single-photon “parents”, a high degree of non-separability may lead to rapid deterioration of the two-photon states after propagation through disorder. In this work, we identify physical mechanisms which contribute to the vulnerability of entangled states in topological photonic lattices. Further, we show that in order to maximize entanglement without sacrificing topological protection, the joint spectral correlation map of two-photon states must fit inside a well-defined topological window of protection.

Highlights

Topological insulators combine insulating properties in the bulk with scattering-free transport along edges, supporting dissipationless unidirectional energy and information flow even in the presence of defects and disorder
In order to maximize the potential of topological photonic networks for transferring quantum information, it is indispensable to have a considerable number of edge modes at our disposal
Phase scrambling can be minimized if the different components of the entangled state travel along the same path in the edge region

Summary

Introduction

Topological insulators combine insulating properties in the bulk with scattering-free transport along edges, supporting dissipationless unidirectional energy and information flow even in the presence of defects and disorder. We analyze possible mechanisms of dissipation of two-photon edge states into the bulk of two different topological insulator system, the Haldane lattice model and an aperiodic lattice corresponding to the quantum Hall effect.

Results

Conclusion