  Exploring controllable interactions lies at the heart of quantum science.
Neutral Rydberg atoms provide a versatile route toward flexible interactions
between single quanta. Previous efforts mainly focused on the excitation
annihilation~(EA) effect of the Rydberg blockade due to its robustness against
interaction fluctuation. We study another effect of the Rydberg blockade,
namely, the transition slow-down~(TSD). In TSD, a ground-Rydberg cycling in one
atom slows down a Rydberg-involved state transition of a nearby atom, which is
in contrast to EA that annihilates a presumed state transition. TSD can lead to
an accurate controlled-{\footnotesize NOT}~({\footnotesize CNOT}) gate with a
sub-$\mu$s duration about $2\pi/\Omega+\epsilon$ by two pulses, where
$\epsilon$ is a negligible transient time to implement a phase change in the
pulse and $\Omega$ is the Rydberg Rabi frequency. The speedy and accurate
TSD-based {\footnotesize CNOT} makes neutral atoms comparable~(superior) to
superconducting~(ion-trap) systems.
