Non-local skyrmions as topologically resilient quantum entangled states of light

By Pedro Ornelas, I. Nape, R. de Mello Koch, Andrew Forbes. Nature Photonics, 2022

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In the early 1960s, inspired by developing notions of topological structure, Tony Skyrme suggested that sub-atomic particles can be described as natural excitations of a single quantum field. Although never adopted for its intended purpose, the notion of a skyrmion as a topologically stable field configuration has proven to be highly versatile, finding application in condensed-matter physics, acoustics and more recently, optics, but it has been realized as localized fields and particles in all instances. Here we report the first non-local quantum entangled state with a non-trivial topology that is skyrmionic in nature, even though each individual photon has no salient topological structure. We demonstrate how the topology makes such quantum states robust to smooth deformations of the wavefunction, remaining intact until the entanglement itself vanishes. Our work points to a nascent connection between entanglement classes and topology, opens exciting questions into the nature of map-preserving quantum channels and offers a promising avenue for the preservation of quantum information by topologically engineered quantum states that persist even when entanglement is fragile. A skyrmion is a topologically stable field configuration. A non-local skyrmion, which has been hitherto elusive in condensed-matter physics, is realized by using entangled photons with a non-trivial topology. The connection between the notions of topology and entanglement is investigated, revealing topological invariance even when entanglement is fragile.

Subfields: Artificial Intelligence, Atomic and Molecular Physics, and Optics

View Paper: https://www.semanticscholar.org/paper/341373dd4b75ffbb2d6de762c121c8900671d19e