Decoherence of dielectric particles by thermal emission

TL;DR

This paper develops a master equation to describe how thermal emission causes decoherence in the quantum states of dielectric particles, revealing that shape and material properties influence localization of superpositions.

Contribution

It introduces a novel theoretical framework for understanding thermal emission-induced decoherence in arbitrarily shaped dielectric rotors, extending beyond point particles.

Findings

Thermal emission leads to localization of superpositions based on material and shape.

Isotropic particles are not inherently protected from decoherence by symmetry.

The theory applies to particles of any size and shape, predicting decoherence effects.

Abstract

Levitated nanoparticles are a promising platform for sensing applications and for macroscopic quantum experiments. While the nanoparticles' motional temperatures can be reduced to near absolute zero, their uncontrolled internal degrees of freedom remain much hotter, inevitably leading to the emission of heat radiation. The decoherence and motional heating caused by this thermal emission process is still poorly understood beyond the case of the center-of-mass motion of point particles. Here, we present the master equation describing the impact of heat radiation on the motional quantum state of arbitrarily sized and shaped dielectric rigid rotors. It predicts the localization of spatio-orientational superpositions only based on the bulk material properties and the particle geometry. A counter-intuitive and experimentally relevant implication of the presented theory is that orientational superpositions of optically isotropic bodies are not protected by their symmetry, even in the small-particle limit.