Optimal control of coherent light scattering for binary decision problems

TL;DR

This paper develops a framework to optimize coherent light fields for binary decision problems in scattering systems, achieving significantly reduced photon usage by approaching the Helstrom bound.

Contribution

It introduces a general method to calculate and minimize the Helstrom bound using tailored coherent fields and experimentally demonstrates its effectiveness in a scattering media scenario.

Findings

Optimal fields identified via scattering matrix measurements.

Over two orders of magnitude reduction in photon number needed.

Experimental validation of the framework's effectiveness.

Abstract

Due to quantum noise fluctuations, the rate of error achievable in decision problems involving several possible configurations of a scattering system is subject to a fundamental limit known as the Helstrom bound. Here, we present a general framework to calculate and minimize this bound using coherent probe fields with tailored spatial distributions. As an example, we experimentally study a target located in between two disordered scattering media. We first show that the optimal field distribution can be directly identified using a general approach based on scattering matrix measurements. We then demonstrate that this optimal light field successfully probes the presence of the target with a number of photons that is reduced by more than two orders of magnitude as compared to unoptimized fields.