Probing nonorthogonality of eigenfunctions and its impact on transport through open systems

The degree of nonorthogonality of eigenstates of non-Hermitian systems governs nuclear scattering, electronic conductance, and wave propagation in disordered media. Here, we determine the impact of non-Hermiticity upon eigenstates inside an open random cavity from measurements of the modal overlap matrix of transmitted microwave radiation. Increasing eigenfunction correlation with spectral modal overlap brought about by the openness of the system leads to modal transmission greatly exceeding unity accompanied by strong modal anticorrelation guaranteeing that transmission does not exceed unity.