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arXiv · 2510.13035

Coherent Control of Wave Scattering via Minimal-Parameter Tuning of Complex Spectra

Ali H. Alhulaymi·Nazar Pyvovar·Philipp del Hougne·Owen D. Miller·A. Douglas Stone
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Abstract

We introduce and validate a theoretical framework for coherent control of multichannel linear scattering to route waves through complex geometries with multiple scattering. We show that steady-state perfect routing solutions are achievable at any frequency via tuning geometric parameters so that multiple complex eigenfrequencies coincide on the real axis. The relevant complex spectra describe critically constrained scattering processes (CCONs), where a specific number of generically accessible outgoing channels are inaccessible due to destructive interference. Focusing on electromagnetic waves, we demonstrate in simulations routing and demultiplexing with high discrimination of signals in a multiport chaotic cavity with a small number of tunable scatterers and free-space signal routing in a grating coupler with a similar number of tunable elements in its unit cell. The minimal number of tuning parameters required is predicted by codimension arguments and validated in simulations. A special class of perfect reflection processes are found to be enhanced in the presence of time-reversal symmetry. A similar approach can be used to implement other interesting functionalities, such as isolation, power division, mode conversion and filtering. The method can be applied to other classical waves and also to quantum matter waves.

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Ali H. Alhulaymi, Nazar Pyvovar, Philipp del Hougne, Owen D. Miller, A. Douglas Stone. 2025-10-14. Coherent Control of Wave Scattering via Minimal-Parameter Tuning of Complex Spectra. https://arxiv.org/abs/2510.13035

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