Induced Time-Reversal Symmetry Breaking Observed in Microwave Billiards

TL;DR

This paper demonstrates the experimental observation of time-reversal symmetry breaking in microwave billiards caused by a ferrite, using a scattering matrix model to analyze the effects on nearly degenerate resonances.

Contribution

It provides the first experimental measurement of T-violation matrix elements in microwave billiards with embedded ferrites, linking magnetization to symmetry breaking.

Findings

T-violation affects pairs of nearly degenerate resonances but not isolated ones

Scattering matrix model successfully describes T-violation effects

T-violating matrix elements depend on ferrite magnetization

Abstract

Using reciprocity, we investigate the breaking of time-reversal (T) symmetry due to a ferrite embedded in a flat microwave billiard. Transmission spectra of isolated single resonances are not sensitive to T-violation whereas those of pairs of nearly degenerate resonances do depend on the direction of time. For their theoretical description a scattering matrix model from nuclear physics is used. The T-violating matrix elements of the effective Hamiltonian for the microwave billiard with the embedded ferrite are determined experimentally as functions of the magnetization of the ferrite.