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Variable potentials for thermalized light and coupled condensates


Quantum gases in lattice potentials have been a powerful platform to simulate phenomena from solid-state physics, such as the Mott insulator transition1. In contrast to ultracold atoms, photon-based platforms, such as photonic crystals, coupled waveguides or lasers, usually do not operate in thermal equilibrium2,3,4,5. Advances towards photonic simulators of solid-state equilibrium effects include polariton lattice experiments6,7,8,9,10, and the demonstration of a photon condensate11,12. Here, we demonstrate a technique to create variable micropotentials for light using thermo-optic imprinting of a dye–polymer solution within an ultrahigh-finesse microcavity. We study the properties of single- and double-well potentials, and find the quality of structuring sufficient for thermalization and Bose–Einstein condensation of light. The investigation of effective photon–photon interactions along with the observed tunnel coupling between sites makes the system a promising candidate to directly populate entangled photonic many-body states. The demonstrated scalability suggests that thermo-optic imprinting provides a new approach for variable microstructuring in photonics.

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Figure 1: Set-up and lattice realizations.
Figure 2: Thermalization, condensation and photon self-interactions in a single microsite.
Figure 3: Tunnelling between two microsites.
Figure 4: Eigenstate hybridization in a double-well.


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We thank U. Fischer for valuable discussions on the thermal model. Financial support by the Deutsche Forschungsgemeinschaft (Collaborative Research Centre 185) and the European Research Council (Interacting Photon Bose–Einstein Condensates in Variable Potentials—INPEC) is acknowledged.

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Authors and Affiliations



D.D., C.K., T.D., J.S., F.V. and J.K. analysed the data. D.D., M.W. and J.K. conceived and designed the experiments. D.D., C.K., T.D., J.S. and J.K. contributed materials/analysis tools. D.D., C.K., J.S. and J.K. performed the experiments. D.D., F.V., M.W. and J.K. wrote the paper.

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Correspondence to Martin Weitz or Jan Klaers.

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The authors declare no competing financial interests.

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Dung, D., Kurtscheid, C., Damm, T. et al. Variable potentials for thermalized light and coupled condensates. Nature Photon 11, 565–569 (2017).

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