Optimal orientation detection of an anisotropic dipolar scatterer

TL;DR

This paper proposes an optimal measurement scheme for determining the orientation of an anisotropic dipolar scatterer, achieving Heisenberg-limited precision and enabling ground-state cooling of its rotational degrees of freedom.

Contribution

It introduces a theoretically optimal measurement scheme for anisotropic scatterer orientation detection and demonstrates its feasibility for ground-state cooling in optical traps.

Findings

Imprecision-backaction product reaches Heisenberg limit

Feasibility of measurement-based ground-state cooling

Realistic measurement scheme proposed

Abstract

The angular orientation of an anisotropic scatterer with cylindrical symmetry in a linearly polarized light field represents an optomechanical librator. Here, we propose and theoretically analyze an optimal measurement scheme for the two angular degrees of freedom of such a librator. The imprecision-backaction product of this scheme reaches the Heisenberg uncertainty limit. Furthermore, we propose and analyze a realistic measurement scheme and show that, in the absence of spinning motion around the symmetry axis, measurement-based ground-state cooling of the rotational degrees of freedom of an anisotropic point scatterer levitated in an optical trap is feasible.