论文标题
在扩散状态之外的波散射中的平均路径长度不变性
Mean path length invariance in wave-scattering beyond the diffusive regime
论文作者
论文摘要
扩散的随机步行具有令人惊讶的属性，即进入和退出有限域的所有可能随机轨迹的平均长度仅由域边界决定。扩散常数或无平均路径的变化，该路径表征了扩散过程，将平均路径长度保持不变。在这里，我们在实验上证明，即使波浪干扰导致与扩散过程明显偏差，也可以将该结果转移到波的散射中。使用多功能微波设置，我们建立了与安德森本地化的跨界以及光子晶体中带隙的平均路径长度不变性。与基于基于完整的散射矩阵的评估相比，我们仅基于传输矩阵测量的平均路径长度来获得这些结果，该过程对吸收和不完整的测量更为强大。
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 novel 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.
