Quantum limits to mass sensing in a gravitational field

TL;DR

This paper investigates the fundamental quantum limits of measuring a particle's mass in a gravitational field, analyzing how quantum states and external fields influence measurement precision.

Contribution

It quantifies the ultimate bounds on mass sensing precision in gravitational fields using Quantum Fisher Information, highlighting the advantage of non-classical states.

Findings

Quantum states without classical limits outperform semiclassical states.

Stronger gravitational fields generally improve measurement precision.

Position measurements in freely-falling systems are an exception to this trend.

Abstract

We address the problem of estimating the mass of a quantum particle in a gravitational field and seek the ultimate bounds to precision of quantum-limited detection schemes. In particular, we study the effect of the field on the achievable sensitivity and address the question of whether quantumness of the probe state may provide a precision enhancement. The ultimate bounds to precision are quantified in terms of the corresponding Quantum Fisher Information. Our results show that states with no classical limit perform better than semiclassical ones and that a non-trivial interplay exists between the external field and the statistical model. More intense fields generally lead to a better precision, with the exception of position measurements in the case of freely-falling systems.