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Main Authors: Zhu, Pengfei, Lecompagnon, Julien, Hirsch, Philipp Daniel, Ziegler, Mathias, Mandelis, Andreas
Format: Preprint
Published: 2026
Subjects:
Online Access:https://arxiv.org/abs/2603.24094
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_version_ 1866915889659510784
author Zhu, Pengfei
Lecompagnon, Julien
Hirsch, Philipp Daniel
Ziegler, Mathias
Mandelis, Andreas
author_facet Zhu, Pengfei
Lecompagnon, Julien
Hirsch, Philipp Daniel
Ziegler, Mathias
Mandelis, Andreas
contents Snell law is traditionally regarded as a hallmark of phase-propagating phenomena such as optical, acoustic, elastic, electromagnetic, and quantum waves. In contrast, purely diffusive processes, such as Fourier heat conduction and chemical diffusion, are generally considered incapable of exhibiting refractive/reflective behavior. In this letter, we demonstrate that although diffusion waves including thermal diffusion, mass diffusion, Lindblad quantum diffusion, and electromagnetic diffusion do not follow Snell law in either time or frequency-domain, nevertheless they obey a spectral form of Snell law which reveals a hidden analog of wave refraction/reflection within the mathematical structure of diffusion dynamics. Remarkably, the spectral refraction ratio is governed not by the diffusion coefficient itself but by the constitutive relations of the media across the interface, establishing a new physical paradigm for diffusion-wave fields. Importantly, while each spectral eigenmode satisfies a rigorous Snell-type refraction relation, the inverse Fourier-Laplace transformation mixes these modes and suppresses any persistent real-space refraction angle, thereby reconciling the modal-level directionality with the long-standing absence of geometric refraction in diffusive systems.
format Preprint
id arxiv_https___arxiv_org_abs_2603_24094
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle The Spectral Domain Snell Law in Diffusion-Wave Fields
Zhu, Pengfei
Lecompagnon, Julien
Hirsch, Philipp Daniel
Ziegler, Mathias
Mandelis, Andreas
Optics
Applied Physics
Snell law is traditionally regarded as a hallmark of phase-propagating phenomena such as optical, acoustic, elastic, electromagnetic, and quantum waves. In contrast, purely diffusive processes, such as Fourier heat conduction and chemical diffusion, are generally considered incapable of exhibiting refractive/reflective behavior. In this letter, we demonstrate that although diffusion waves including thermal diffusion, mass diffusion, Lindblad quantum diffusion, and electromagnetic diffusion do not follow Snell law in either time or frequency-domain, nevertheless they obey a spectral form of Snell law which reveals a hidden analog of wave refraction/reflection within the mathematical structure of diffusion dynamics. Remarkably, the spectral refraction ratio is governed not by the diffusion coefficient itself but by the constitutive relations of the media across the interface, establishing a new physical paradigm for diffusion-wave fields. Importantly, while each spectral eigenmode satisfies a rigorous Snell-type refraction relation, the inverse Fourier-Laplace transformation mixes these modes and suppresses any persistent real-space refraction angle, thereby reconciling the modal-level directionality with the long-standing absence of geometric refraction in diffusive systems.
title The Spectral Domain Snell Law in Diffusion-Wave Fields
topic Optics
Applied Physics
url https://arxiv.org/abs/2603.24094