Achieving quantum-limited optical resolution

TL;DR

This paper introduces a method to surpass the Rayleigh limit in optical resolution by using quantum Fisher information and optimal measurement strategies, confirmed through experimental demonstrations with digital holography.

Contribution

It presents a new approach to achieve quantum-limited resolution by identifying optimal measurement bases and experimentally validating sub-Rayleigh precision.

Findings

Surpassing Rayleigh limit with coherent measurements

Explicit optimal measurement strategies for Gaussian and slit apertures

Experimental confirmation of sub-Rayleigh resolution

Abstract

We establish a simple method to assess the quantum Fisher information required for resolving two incoherent point sources with an imaging system. The resulting Cram\'er-Rao bound shows that the standard Rayleigh limit can be surpassed by suitable coherent measurements. We explicitly find these optimal strategies and present a realization for Gaussian and slit apertures. This involves a projection onto the optimal bases that is accomplished with digital holographic techniques and is compared with a CCD position measurement. Our experimental results unequivocally confirm unprecedented sub-Rayleigh precision.