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Causality and Instability in Wave Propagation in Random Time-Varying Media
R Pierrat1, J Rocha1, R Carminati1,2
1PSL University, ESPCI Paris, Institut Langevin, CNRS, 1 rue Jussieu, 75005 Paris, France.
Physical Review Letters
|June 27, 2025
Summary
This study models wave propagation in time-varying media, finding causality prevents recurrent scattering. The research offers insights into wave dynamics and applications in dynamic sensing and metamaterials.
Area of Science:
- Wave propagation
- Theoretical physics
- Disordered media
Background:
- Wave dynamics in media with random properties are complex.
- Temporal fluctuations cause intricate scattering.
- Understanding these dynamics is crucial for advanced applications.
Purpose of the Study:
- To develop a theoretical model for wave propagation in media with random time-varying properties.
- To investigate the effects of temporal disorder on wave scattering.
- To provide a nonperturbative solution for the average Green's function.
Main Methods:
- Development of a theoretical model for wave propagation.
- Derivation of an exact expression for the ensemble-averaged Green's function.
- Analysis extended to the thermodynamic limit.
- Introduction of an effective medium description.
Main Results:
- An exact expression for the average Green's function in finite temporal disorder was derived.
- Causality was shown to prevent recurrent scattering, enabling a nonperturbative solution.
- Propagation regimes were analyzed using an effective medium description.
Conclusions:
- The study provides new insights into wave dynamics in temporally disordered media.
- Findings have potential applications in time-varying metamaterials and dynamic sensing.
- The theoretical framework can aid imaging in turbulent or chaotic environments.
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