Distribution of the S-matrix in chaotic microwave cavities with direct processes and absorption

TL;DR

This paper investigates how direct processes and absorption influence the distribution of the S-matrix in chaotic microwave cavities, combining experiments, simulations, and theoretical models to validate predictions.

Contribution

It provides a generalized Poisson kernel for the S-matrix distribution in cavities with absorption and direct processes, validated by experiments and simulations.

Findings

Experimental and numerical distributions match random-matrix predictions.

The generalized Poisson kernel accurately describes the S-matrix distribution.

Absorption and direct processes significantly affect the S-matrix statistics.

Abstract

We quantify the presence of direct processes in the S-matrix of chaotic microwave cavities with absorption in the one-channel case. To this end the full distribution P_S(S) of the S-matrix, i.e. S=\sqrt{R}e^{i\theta}, is studied in cavities with time-reversal symmetry for different antenna coupling strengths T_a or direct processes. The experimental results are compared with random-matrix calculations and with numerical simulations based on the Heidelberg approach including absorption. The theoretical result is a generalization of the Poisson kernel. The experimental and the numerical distributions are in excellent agreement with random-matrix predictions for all cases.