Destructive Quantum Interference and Exceptional Points in High-frequency Response of Two-state System

We consider the high-frequency conductance of a two-state quantum system within non-equilibrium Green function formalism. Multiply connected configurations possessing Fano-Feshbach antiresonances in stationary transmission show trivial behavior in the dynamical regime. Whereas the simply connected linear configuration, demonstrates an exceptional point in dynamics and destructive quantum interference for frequency equal the energy split between the eigenstates. This is manifestation of “synthetic dimension” introduced by the Floquet quasienergy spectrum.