Near optimal discrimination of binary coherent signals via atom-light interaction

TL;DR

This paper proposes a nondestructive atom-light interaction scheme that nearly reaches the Helstrom bound for discriminating binary coherent light states, enabling highly accurate quantum state discrimination with potential for sequential measurements.

Contribution

It introduces a method using Jaynes-Cummings interaction and atomic measurements to nearly achieve optimal quantum discrimination of weak coherent states.

Findings

Achieves error probability close to the Helstrom bound

Uses Jaynes-Cummings interaction for optimal atom-light coupling

Allows sequential measurements due to nondestructive light measurement

Abstract

We study the discrimination of weak coherent states of light with significant overlaps by nondestructive measurements on the light states through measuring atomic states that are entangled to the coherent states via dipole coupling. In this way, the problem of measuring and discriminating coherent light states is shifted to finding the appropriate atom-light interaction and atomic measurements. We show that this scheme allows us to attain a probability of error extremely close to the Helstrom bound, the ultimate quantum limit for discriminating binary quantum states, through the simple Jaynes-Cummings interaction between the field and ancilla with optimized light-atom coupling and projective measurements on the atomic states. Moreover, since the measurement is nondestructive on the light state, information that is not detected by one measurement can be extracted from the post-measurement light states through subsequent measurements.