A topological light funnel

Because most physical systems cannot be totally isolated from their environment, some degree of dissipation or loss is expected. The successful operation of such systems generally relies on mitigating for that loss. Mathematically, such external interactions are described as non-Hermitian. Recent work has shown that controlling the gain and loss in these systems gives rise to a wide variety of exotic phenomena not expected for their isolated Hermitian counterparts. Using a time-dependent photonic lattice in which the topological properties can be controlled, Weidemann et al. show that such a structure can efficiently funnel light to the interface irrespective of the point of incidence on the lattice. Such control of the topological properties could be useful for nanophotonic applications in integrated optical chip platforms.
Science, this issue p. 311


Dissipation is a general feature of non-Hermitian systems. But rather than being an unavoidable nuisance, non-Hermiticity can be precisely controlled and hence used for sophisticated applications, such as optical sensors with enhanced sensitivity. In our work, we implement a non-Hermitian photonic mesh lattice by tailoring the anisotropy of the nearest-neighbor coupling. The appearance of an interface results in a complete collapse of the entire eigenmode spectrum, leading to an exponential localization of all modes at the interface. As a consequence, any light field within the lattice travels toward this interface, irrespective of its shape and input position. On the basis of this topological phenomenon, called the “non-Hermitian skin effect,” we demonstrate a highly efficient funnel for light.

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Supplementary Material


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Published In

Volume 368 | Issue 6488
17 April 2020

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Submission history

Received: 16 October 2019
Accepted: 3 February 2020
Published in print: 17 April 2020


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We thank M. Wimmer for very useful discussions. Funding: The authors acknowledge funding from the Deutsche Forschungsgemeinschaft (BL 574/13-1, SZ 276/19-1, SZ 276/20-1, SZ 276/9-2, and 258499086–SFB 1170), the Würzburg-Dresden Cluster of Excellence on Complexity and Topology in Quantum Matter ct.qmat (39085490–EXC 2147), and the Alfried Krupp von Bohlen und Halbach Foundation. Author contributions: M.K. developed the theory and S.W. performed the experiments on the photonic mesh lattice. R.T. and A.S. supervised the project. All authors discussed the results and co-wrote the paper. The manuscript reflects the contributions of all authors. Competing interests: The authors declare that they have no competing interests. Data and materials availability: All experimental data and any related experimental background information not mentioned in the text can be found at the Rostock University Publication Server repository (30).



Institute of Physics, University of Rostock, 18059 Rostock, Germany.
Institute of Physics, University of Rostock, 18059 Rostock, Germany.
Tobias Helbig
Department of Physics and Astronomy, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
Tobias Hofmann
Department of Physics and Astronomy, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
Alexander Stegmaier
Department of Physics and Astronomy, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
Department of Physics and Astronomy, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
Department of Physics and Astronomy, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
Institute of Physics, University of Rostock, 18059 Rostock, Germany.

Funding Information

Deutsche Forschungsgemeinschaft: 258499086 - SFB 1170
Deutsche Forschungsgemeinschaft: 39085490 - EXC 2147
Deutsche Forschungsgemeinschaft: 258499086 - SFB 1170
Deutsche Forschungsgemeinschaft: 39085490 - EXC 2147


These authors contributed equally to this work.
Corresponding author. Email: [email protected]

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