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Topological Protection of Bell States in a Two-Dimensional Quantum Walk

Liat Nemirovsky-Levy, Mark D. Lyubarov, Yonatan Plotnik, Ohad Segal, Mordechai Segev

Published Jan 1, 2024• 0 citations
Publisher

Abstract

We present a method to protect the entanglement of a Bell-state encoded on a single photon performing a two-dimensional discrete-time quantum walk. We find an edge-state at the boundary of two distinct quantum walk domains.
DOI
10.1364/cleo_fs.2024.fw3m.4

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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", high degree of non-separability may lead to rapid deterioration of the two-photon states after propagation through disorder. We identify physical mechanisms which contribute to the vulnerability of entangled states in topological photonic lattices and present clear guidelines for maximizing entanglement without sacrificing topological protection.
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