Quantum-noise-limited Angular Momentum Measurement for a Micron-sized Dielectric Object

TL;DR

This paper proposes a method to observe quantum features of micron-sized dielectric objects by measuring their angular momentum noise through birefringence, enabling quantum nondemolition measurements similar to atomic spin systems.

Contribution

It introduces a novel optical technique for quantum noise measurement of a micron-sized dielectric top, extending quantum measurement methods to macroscopic objects.

Findings

Angular momentum noise can be measured via birefringence-induced phase shifts.

The method enables quantum nondemolition measurements of micron-sized objects.

Optical trapping and alignment of the dielectric object are feasible for quantum experiments.

Abstract

An approach is described for observing quantum features of micron-sized spinning objects. Specifically, we consider a birefringent (uniaxial positive) dielectric object in the shape of an oblate (i.e., frisbee-like) symmetric top. It can be trapped in the air, its extraordinary axis can be aligned, and its angular momentum along the extraordinary axis can be stabilized, all optically. We show that the angular momentum quantum noise of the object perpendicular to the gigantic angular momentum along the extraordinary axis can be measured as a linear birefringent phase shift of a probe laser in an analogous fashion to the spin quantum nondemolition (QND) measurement in atomic physics.