Spatial decomposition of displacement signals in scattered light of a levitated nanoparticle
Phys. Rev. A 114, 033509 – Published 9 September, 2026
DOI: https://doi.org/10.1103/ttt1-zc8g
Abstract
Efficient measurement of center-of-mass motion is fundamental to force sensing and quantum control in levitated optomechanics. While scattering theories predict the spatial distribution of displacement information, direct experimental mapping of this information remains undemonstrated, leaving uncertainties regarding the impact of real-world optical imperfections. Here, we introduce a spatial-scanning technique to experimentally visualize the three-dimensional displacement information distribution of a levitated nanoparticle. By decomposing the scattered field into independent motional axes, we reconstruct the information radiation patterns, which reveal the angular density of detectable information. The measured patterns agree well with theoretical calculations while capturing minor distortions attributed to experimental imperfections. Furthermore, we demonstrate that the integrated displacement information remains robust against variations in the detection plane position along the optical axis. This work establishes a direct approach to characterizing information flow in scattered light, providing a practical framework for optimizing detection efficiency in complex or nonstandard optomechanical systems.
