  Electrons confined in semiconductor quantum dot arrays have both charge and
spin degrees of freedom. The spin provides a well-controllable and long-lived
qubit implementation. The charge configuration in the dot array is influenced
by Coulomb repulsion, and the same interaction enables charge sensors to probe
this configuration. Here we show that the Coulomb repulsion allows an initial
charge transition to induce subsequent charge transitions, inducing a cascade
of electron hops, like toppling dominoes. A cascade can transmit information
along a quantum dot array over a distance that extends by far the effect of the
direct Coulomb repulsion. We demonstrate that a cascade of electrons can be
combined with Pauli spin blockade to read out spins using a remote charge
sensor. We achieve > 99.9% spin readout fidelity in 1.7 $\mathrm{\mu}$s. The
cascade-based readout enables operation of a densely-packed two-dimensional
quantum dot array with charge sensors placed at the periphery. The high
connectivity of such arrays greatly improves the capabilities of quantum dot
systems for quantum computation and simulation.
