Playing Pool with $|\psi \rangle$: from Bouncing Billiards to Quantum Search

Abstract

In "Playing Pool with $\pi$", Galperin invented an extraordinary method to learn the digits of $\pi$ by counting the collisions of billiard balls. Here I demonstrate an exact isomorphism between Galperin's bouncing billiards and Grover's algorithm for quantum search. This provides an illuminating way to visualize Grover's algorithm.