Mainz 2026 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 18: Photon BEC
Q 18.4: Talk
Tuesday, March 3, 2026, 11:45–12:00, P 4
Limit Cycles Driven by non-Hermitian Interactions in Coupled Photon Condensates — •Kevin Peters1, Peter Schnorrenberg2, Daniel Ehrmanntraut1,2, Nikolas Longen1,2, and Julian Schmitt2 — 1Universität Bonn, Institut für Angewandte Physik, Wegelerstr. 8, 53115 Bonn, Germany — 2Universität Heidelberg, Kirchhoff Institut für Physik, Im Neuenheimer Feld 227, 69120 Heidelberg
We report the first observation of limit cycle oscillations in photon condensates. In our experiments, photons were trapped in two coherently coupled, dye-filled optical microcavities forming a photonic dimer. Previous work has demonstrated Bose-Einstein condensation of the photons into the symmetric ground state of the dye-filled dimer above a critical photon number for the case of spatially uniform pumping. Here we report on the observation of emergent, self-sustained dynamics under inhomogeneous excitation. When only a single site of the dimer is pumped, we experimentally observe spontaneous oscillations in the photon number at both sites, appearing over a range of pump powers. We show that these oscillations are the result of stable limit cycles associated with a parametric instability predicted by theory. Unlike in Kerr and thermo-optical nonlinear cavities, the instability in the dye-microcavity system is driven by effective imaginary photon-photon interactions. These non-Hermitian interactions are mediated by the dye molecules, and their strength can be conveniently tuned via the cut-off frequency imposed by the cavity length.
Keywords: limit cycles; non-hermitian; emergent; nonlinear optics; collective