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arXiv · 2512.06544

Observed enhanced emission at higher-order exceptional points in RF circuits

Nicolas Wyszkowski·Arunn Suntharalingam·Max Vitek·Arkady Kurnosov·Lucas J. Fernández-Alcázar·Tsampikos Kottos
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Abstract

The Purcell effect -- stemming directly from the celebrated Fermi's Golden Rule -- links the enhanced emissivity of an emitter to the local density of states (LDoS) of a surrounding cavity. Under typical circumstances the LDoS is assumed to have a Lorentzian lineshape. Here, we go beyond the traditional Purcell framework by designing RF cavities with non-Lorentzian LDoS caused by higher-order non-Hermitian exceptional point degeneracies (EPDs) where $N\geq 2$ eigenfrequencies and their associated eigenmodes coalesce. We experimentally demonstrate a non-conventional emissivity enhancement (as compared to the isolated resonance regime) that increases with the EPD order $N$. The theoretical analysis traces its origin to an $N$-th power Lorentzian LDoS line shape that dominates under judicious spatially designed cavity losses. Our results reveal a new route to design cavities that do not rely on ultrahigh $Q$-factor resonators or small modal volumes.

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Nicolas Wyszkowski, Arunn Suntharalingam, Max Vitek, Arkady Kurnosov, Lucas J. Fernández-Alcázar, Tsampikos Kottos. 2025-12-06. Observed enhanced emission at higher-order exceptional points in RF circuits. https://arxiv.org/abs/2512.06544

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