Quantum-enhanced passive remote sensing

TL;DR

This paper provides a quantum mechanical analysis of passive microwave remote sensing, demonstrating that quantum techniques can significantly improve spatial resolution and temperature sensitivity in satellite Earth observation.

Contribution

It introduces a fully quantum framework for passive remote sensing, identifying optimal measurement schemes that reach the quantum Cramér-Rao bound, enabling substantial resolution enhancements.

Findings

Quantum enhancement of spatial resolution by over 20 times

Potential resolution down to 1 meter with temperature sensitivity below 0.1 Kelvin

Single measurement and detector can achieve these improvements

Abstract

We investigate theoretically the ultimate resolution that can be achieved with passive remote sensing in the microwave regime used e.g.~on board of satellites observing Earth, such as the Soil Moisture and Ocean Salinity (SMOS) mission. We give a fully quantum mechanical analysis of the problem, starting from thermal distributions of microscopic currents on the surface to be imaged that lead to a mixture of coherent states of the electromagnetic field which are then measured with an array of receivers. We derive the optimal detection modes and measurement schemes that allow one to saturate the quantum Cram\'er-Rao bound for the chosen parameters that determine the distribution of the microscopic currents. For parameters comparable to those of SMOS, a quantum enhancement of the spatial resolution by more than a factor of 20 should be possible with a single measurement and a single detector, and a resolution down to the order of 1 meter and less than a 1/10 Kelvin for the theoretically possible maximum number of measurements.