Magnetic rigid rotor in the quantum regime: Theoretical toolbox

A theoretical framework is developed to study a magnetically levitated nanomagnet in the quantum regime. The system is very rich due to the interaction between its degrees of freedom: position, orientation, and magnetization. In particular, the Einstein--de Haas effect, namely the coupling between the magnetization and the angular momentum of the object, plays a dramatic role. This work sheds new light on one of the few unsolved problem in quantum mechanics, the rigid rotor with a spin. At the same time, it opens up the possibility to model the dynamics of a single magnetic domain nanoparticle in a magnetic trap, an interesting new scenario for future experiments.