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Main Authors: Steinfurth, Andrea, Weidemann, Sebastian, Görsch, Julia, Sheppard, Tom, Price, Hannah M., Szameit, Alexander, Feis, Joshua
Format: Preprint
Published: 2026
Subjects:
Online Access:https://arxiv.org/abs/2604.10486
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author Steinfurth, Andrea
Weidemann, Sebastian
Görsch, Julia
Sheppard, Tom
Price, Hannah M.
Szameit, Alexander
Feis, Joshua
author_facet Steinfurth, Andrea
Weidemann, Sebastian
Görsch, Julia
Sheppard, Tom
Price, Hannah M.
Szameit, Alexander
Feis, Joshua
contents Time is the odd dimension out: Unlike space, it follows the arrow of time, forbidding back-reflections and requiring momentum yet not energy conservation. Tailored temporal variations manipulate momentum bands and engineer waves in time. We show that momentum bands exhibit unique topology, hidden when conventionally considering energy bands: Complex momentum bands may wind, mandating topological localization at time interfaces. We observe this effect in photonic quantum walks and study it under disorder. Remarkably, unlike any known topological phenomenon, the topology is immune against arbitrarily strong disorder. Only exotic conditions through extreme spatiotemporally random non-Hermiticity can destroy it. Our findings uncover a disorder-immune type of topological physics, inviting explorations of complex momentum or energy-momentum topology with potential applications like ultrarobust lasing, temporal pulse shaping or amplification.
format Preprint
id arxiv_https___arxiv_org_abs_2604_10486
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Disorder-immune momentum band winding topology
Steinfurth, Andrea
Weidemann, Sebastian
Görsch, Julia
Sheppard, Tom
Price, Hannah M.
Szameit, Alexander
Feis, Joshua
Optics
Time is the odd dimension out: Unlike space, it follows the arrow of time, forbidding back-reflections and requiring momentum yet not energy conservation. Tailored temporal variations manipulate momentum bands and engineer waves in time. We show that momentum bands exhibit unique topology, hidden when conventionally considering energy bands: Complex momentum bands may wind, mandating topological localization at time interfaces. We observe this effect in photonic quantum walks and study it under disorder. Remarkably, unlike any known topological phenomenon, the topology is immune against arbitrarily strong disorder. Only exotic conditions through extreme spatiotemporally random non-Hermiticity can destroy it. Our findings uncover a disorder-immune type of topological physics, inviting explorations of complex momentum or energy-momentum topology with potential applications like ultrarobust lasing, temporal pulse shaping or amplification.
title Disorder-immune momentum band winding topology
topic Optics
url https://arxiv.org/abs/2604.10486