We study quantum transport in a periodically driven (Floquet) topological system coupled to static fermionic reservoirs. Using the Floquet nonequilibrium Green's-function (NEGF) formalism, we show, from exact numerics for a strip geometry, that the two-terminal (longitudinal) conductance is quantized as $|W_{\varepsilon }|e^2/h$, while the Hall (transverse) conductance is quantized as $W_{\varepsilon }{e}^2/h$, where $W_{\varepsilon }$ is the Floquet winding invariant associated with the quasienergy gap at $\varepsilon =0$ or $\varepsilon =\mathrm{\Omega }/2$. Quantization is achieved only after summing over the contributions of all Floquet sidebands. We provide an analytic understanding of this Floquet conductance sum rule by considering the Hall conductance in the weak-coupling limit. In that limit, we show that the Floquet Hall conductance gets contributions from the Floquet sidebands, with the signs of the velocities of the edge modes taken into account. Their sum yields exact quantization, as predicted by the Floquet sum rule. We find that in a wide range of parameter regimes, the convergence is fast, making observation of the sum rule and Floquet winding numbers accessible to experiments.

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• Quantum transport
• Topological Hall effect
• Floquet systems
• Topological materials
• Nonequilibrium Green's function