Resolving Mutually Coherent Bright Point-Sources

TL;DR

This paper compares direct imaging and spatial mode demultiplexing for resolving mutually coherent point sources, demonstrating the superiority of the latter and its ability to reach quantum-limited sensitivity across various quantum states.

Contribution

It analytically proves the advantage of spatial mode demultiplexing over direct imaging in resolving coherent sources, achieving quantum-limited sensitivity.

Findings

Spatial mode demultiplexing outperforms direct imaging.

Sensitivity saturates quantum Fisher information.

Effective for non-Gaussian quantum states.

Abstract

We analyze the problem of resolving two point-sources in the case of mutually coherent sources with arbitrary quantum statistics, mutual phase, relative and absolute intensity. We use a sensitivity measure based on the method of moments and compare direct imaging with spatial mode demultiplexing, analytically proving the advantage of the latter. We show that the sensitivity of spatial mode demultiplexing saturates the quantum Fisher information, for all known cases, even for non-Gaussian states of the sources.