  The quantum Hall effect occuring in two-dimensional electron gases was first
explained by Laughlin, who envisioned a thought experiment that laid the
groundwork for our understanding of topological quantum matter. His proposal is
based on a quantum Hall cylinder periodically driven by an axial magnetic
field, resulting in the quantized motion of electrons. We realize this
milestone experiment with an ultracold gas of dysprosium atoms, the cyclic
dimension being encoded in the electronic spin and the axial field controlled
by the phases of laser-induced spin-orbit couplings. Our experiment provides a
straightforward manifestation of the non-trivial topology of quantum Hall
insulators, and could be generalized to strongly-correlated topological
systems.
