We consider a possible route to ground state cooling of a levitated nanoparticle, magnetically trapped by a strong permanent magnet, using a combination of measurement and feedback. The trap frequency of this system is much lower than those involving trapped ions or nano-mechanical resonators. Minimisation of environmental heating is therefore challenging as it requires control of the system on a timescale comparable to the inverse of the trap frequency. We show that these traps are an excellent platform for performing optimal feedback control via real-time state estimation, for the preparation of motional states with measurable quantum properties.
@article{arxiv.1903.10470,
title = {Measurement and feedback for cooling heavy levitated particles in low frequency traps},
author = {L. S. Walker and G. R. M. Robb and A. J. Daley},
journal= {arXiv preprint arXiv:1903.10470},
year = {2019}
}