Prospects of phase-adaptive cooling of levitated magnetic particles in a hollow-core photonic-crystal fiber

We analyze the feasibility of cooling of classical motion of a micro- to nano-sized magnetic particle, levitated inside a hollow-core photonic crystal fiber. The cooling action is implemented by means of controlling the relative phase between counterpropagating fiber guided waves. Direct imaging of the particle's position allows dynamic phase adjustments that produce a Stokes-type cooling force. We provide estimates of cooling efficiency and final achievable temperature, taking into account thermal and detection noise sources. Our results bring forward an important step towards using trapped micromagnets in sensing, testing the fundamental physics and preparing the quantum states of magnetization.