Abstract
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.
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The data supporting the findings of this study are available from the corresponding author upon reasonable request.
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The code used to produce the results are available from the corresponding author upon reasonable request.
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Acknowledgements
This work was supported by the South African National Research Foundation/CSIR Rental Pool Programme and the South African Quantum Technology Initiative.
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P.O. and I.N. performed the experiment, and P.O., I.N. and R.M.K. contributed to the theory. All authors contributed to the writing of the manuscript and analysis of data. A.F. conceived of the idea and supervised the project.
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Nature Photonics thanks Cheng-Wei Qiu, Luping Du and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
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Ornelas, P., Nape, I., de Mello Koch, R. et al. Non-local skyrmions as topologically resilient quantum entangled states of light. Nat. Photon. 18, 258–266 (2024). https://doi.org/10.1038/s41566-023-01360-4
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DOI: https://doi.org/10.1038/s41566-023-01360-4
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