Generic transmission zeros and in-phase resonances in time-reversal symmetric single channel transport

We study phase coherent transport in a single channel system using the scattering matrix approach. It is shown that identical vanishing of the transmission amplitude occurs generically in quasi-1D systems if the time-reversal is a good symmetry. The transmission zeros naturally lead to abrupt phase changes (without any intrinsic energy scale) and in-phase resonances, providing insights to recent experiments on phase coherent transport through a quantum dot.