Quantized dynamics in a square-wave-driven coherent single-electron source

Through analytic derivation within the nonequilibrium Green’s function (NEGF) formalism, we present a comprehensive study of a quantum-coherent single-electron emitter. This emitter is based on a quantum RC circuit driven by periodic square-wave potentials with temporal period T and angular frequency ω = 2π/T . Our theoretical results reveal three key characteristics of the single-electron emitter: (i) the characteristic time α of the exponentially decaying current J(t)(∝ e^−t/^α) matches the intrinsic coherence time τ of the quantum dot; (ii) the Fourier spectrum of the current J(mω) carries information of both external driving amplitude U and internal energy levels ϵ_d of the quantum dot; (iii) the quantization of fundamental Fourier component |J₁| = 2ef (f = 1/T ) accompanies the half-quantized relaxation resistance R_q = h/(2e²), featuring quantized dynamics in AC transport through the single-electron emitter. These findings offers new perspectives into the dynamic properties of quantum-coherent AC transport.