What is the complex impedance of a fully coherent quantum resistance-capacitance (RC) circuit at gigahertz frequencies in which a resistor and a capacitor are connected in series? While Kirchhoff’s laws predict addition of capacitor and resistor impedances, we report on observation of a different behavior. The resistance, here associated with charge relaxation, differs from the usual transport resistance given by the Landauer formula. In particular, for a single-mode conductor, the charge-relaxation resistance is half the resistance quantum, regardless of the mode transmission. The new mesoscopic effect reported here is relevant for the dynamical regime of all quantum devices.
J. Gabelli, G. Fève, F.-M. Berroir, B. Plaçais, D.C. Glattli et al.,SciencExpress RE1126940/BPO/PHYSICS