Magnetic Field Asymmetry Of Transport Dynamics In A Coulomb-Coupled Quantum Point Contact

We report phase-resolved microwave magnetotransport measurements of a Coulomb-coupled quantum point contact in the edge state regime. We show that the inductive admittance is manifestly asymmetric under reversal of magnetic field, whereas the field-symmetric conductance is observed. Furthermore, the asymmetry is found to exhibit pronounced fluctuations as a function of magnetic field and transmission. This constitutes direct evidence that kinetic effects associated with the nonequilibrium polarization charge contribute to dynamical magnetoasymmetry in phase-coherent mesoscopic conductors. In addition, we find a striking magnetoasymmetry in the electronic transit time, providing important information about Coulomb coupling effects on quantum dynamics of electrons.