Quantum simulation of wave optics in weakly inhomogeneous media using block-encoding

We propose a quantum algorithm that simulates the propagation of a light field through a weakly inhomogeneous medium. The wave equation in the paraxial approximation in inhomogeneous material takes the form of the Schr\"odinger equation with a time-dependent Hamiltonian. This reduction is used to simulate wave optical dynamics on a quantum computer. Beam propagator operators for a short propagation distance are constructed using an efficient and flexible block-encoding that enables the simulation of various optical setups. The algorithm is showcased by simulating the propagation of a 1D Gaussian beam through a lens with a finite thickness, and the resulting spherical aberrations are demonstrated.