  We show that the quantum Zeno effect gives rise to the Hall effect by
tailoring the Hilbert space of a two-dimensional lattice system into a single
Bloch band with a nontrivial Berry curvature. Consequently, a wave packet
undergoes transverse motion in response to a potential gradient -- a phenomenon
we call the Zeno Hall effect to highlight its quantum Zeno origin. The Zeno
Hall effect leads to retroreflection at the edge of the system due to an
interplay between the band flatness and the nontrivial Berry curvature. We
propose an experimental implementation of this effect with ultracold atoms in
an optical lattice.
