Abstract

Diffusive random walks feature the surprising property that the average length of all possible random trajectories that enter and exit a finite domain is determined solely by the domain boundary. Changes in the diffusion constant or the mean-free path, that characterize the diffusion process, leave the mean path length unchanged. Here, we demonstrate experimentally that this result can be transferred to the scattering of waves, even when wave interference leads to marked deviations from a diffusion process. Using a versatile microwave setup, we establish the mean path length invariance for the crossover to Anderson localization and for the case of a band gap in a photonic crystal. We obtain these results on the mean path length solely based on a transmission matrix measurement through a procedure that turns out to be more robust to absorption and incomplete measurement in the localized regime as compared to an assessment based on the full scattering matrix.

In the diffusive transport regime, the mean path length of waves has been shown to be independent of the microstructure of the medium. Here, this invariance is shown to persist into the ballistic and localized regimes, as well as into the regime of band-gap materials like photonic crystals.

Details

Title
Mean path length invariance in wave-scattering beyond the diffusive regime
Author
Davy Matthieu 1   VIAFID ORCID Logo  ; Kühmayer Matthias 2   VIAFID ORCID Logo  ; Gigan Sylvain 3   VIAFID ORCID Logo  ; Rotter, Stefan 2   VIAFID ORCID Logo 

 Univ. Rennes, CNRS, IETR (Institut d’Électronique et des Technologies du numéRique), Rennes, France (GRID:grid.410368.8) (ISNI:0000 0001 2191 9284) 
 Vienna University of Technology (TU Wien), Institute for Theoretical Physics, Vienna, Austria (GRID:grid.5329.d) (ISNI:0000 0001 2348 4034) 
 Laboratoire Kastler Brossel, Sorbonne Université, École Normale Supérieure, Collège de France, CNRS UMR 8552, Paris, France (GRID:grid.462576.4) (ISNI:0000 0004 0368 5631) 
Publication year
2021
Publication date
2021
Publisher
Nature Publishing Group
e-ISSN
23993650
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2517102782
Copyright
© The Author(s) 2021. This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.