Magnetic field fluctuations induced decoherence of a diamagnetic nanosphere

TL;DR

This paper derives a simple formula for the decoherence rate of a diamagnetic nanoparticle caused by magnetic field fluctuations, aiding understanding of quantum coherence in levitated systems.

Contribution

It provides a novel, straightforward derivation of decoherence rates for diamagnetic nanoparticles in thermal magnetic environments, using the fluctuation-dissipation theorem.

Findings

Decoherence rate is analogous to dielectric interaction with electric fields.

Decoherence is often suppressed due to material properties.

The formula aids in estimating coherence times in magnetic levitation experiments.

Abstract

This paper provides a simple derivation of the decoherence rate for a diamagnetic nanoparticle in the presence of fluctuations of the magnetic field in a thermal environment. Diamagnetic levitation is one of the key techniques for trapping, cooling, and creating a macroscopic quantum spatial superposition in many experiments. It is widely applied in many theoretical and experimental endeavours to test fundamental physics in matter-wave interferometers. To estimate the decoherence rate originating from magnetic-field fluctuations, we use the fluctuation-dissipation theorem. We show that our resulting decoherence rate expression is analogous to that of a dielectric material interacting with the electric field component of the background field; however, it is often relatively suppressed due to the material properties.