Topological mode conservation and conversion in phononic crystals with temporal interfaces

Fuente: arXiv
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Main Authors: Samak, Mahmoud M., Bilal, Osama R.
Format: Preprint
Published: 2026
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author Samak, Mahmoud M.
Bilal, Osama R.
author_facet Samak, Mahmoud M.
Bilal, Osama R.
contents A sudden change in material properties creates a temporal interface and forces a propagating wave to change its frequency while preserving its wavenumber. In contrast to monoatomic lattices with a single frequency-wavenumber pair, polyatomic lattices support multiple frequencies for each wavenumber. To date, experimental observations are limited to topologically trivial monoatomic phononic systems. Here, we utilize analytical, numerical, and experimental methods to examine topologically non-trivial phononic lattices subject to temporal interfaces. In particular, we realize phononic lattices demonstrating single-frequency shift (i.e., mode conservation) and multi-frequency splitting (i.e., mode conversion) following a temporal interface. Accordingly, we generalize temporal analogues of Snell's law and Fresnel equations. Moreover, we utilize Bloch mode overlaps to obtain a phononic time lens and a classical analogue of dynamic quantum phase transitions for phonons. Such overlap determines the probability of mode conversion or conservation after a temporal interface and, more importantly, can carry hidden topological characteristics. Our methodology paves the way for the use of temporal interfaces in probing phonon band topology and the realization of advanced acoustic devices.
format Preprint
id arxiv_https___arxiv_org_abs_2601_08866
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Topological mode conservation and conversion in phononic crystals with temporal interfaces
Samak, Mahmoud M.
Bilal, Osama R.
Classical Physics
A sudden change in material properties creates a temporal interface and forces a propagating wave to change its frequency while preserving its wavenumber. In contrast to monoatomic lattices with a single frequency-wavenumber pair, polyatomic lattices support multiple frequencies for each wavenumber. To date, experimental observations are limited to topologically trivial monoatomic phononic systems. Here, we utilize analytical, numerical, and experimental methods to examine topologically non-trivial phononic lattices subject to temporal interfaces. In particular, we realize phononic lattices demonstrating single-frequency shift (i.e., mode conservation) and multi-frequency splitting (i.e., mode conversion) following a temporal interface. Accordingly, we generalize temporal analogues of Snell's law and Fresnel equations. Moreover, we utilize Bloch mode overlaps to obtain a phononic time lens and a classical analogue of dynamic quantum phase transitions for phonons. Such overlap determines the probability of mode conversion or conservation after a temporal interface and, more importantly, can carry hidden topological characteristics. Our methodology paves the way for the use of temporal interfaces in probing phonon band topology and the realization of advanced acoustic devices.
title Topological mode conservation and conversion in phononic crystals with temporal interfaces
topic Classical Physics
url https://arxiv.org/abs/2601.08866