Levitated Nanomagnets in the Quantum Regime: Theory and Applications
Abstract: In this talk we will discuss the theory and potential applications of levitated nanomagnets in the quantum regime. First, we will show that the quantum dynamics of the degrees of freedom of a nanomagnet (magnetization, rotational, and center-of-mass motion) near an equilibrium point can be described with a six-mode quadratic Hamiltonian where one magnonic, two rotonic, and three phononic modes are strongly coupled. We will then show that a non-rotating nanomagnet can be stably levitated in a static field configuration, despite Earnshaw's theorem. The quantum origin of the magnetzation, namely the gyromagnetic effect, plays a decisive role in the linear stability analysis of the system. Regarding applications, we will discuss an interface between a nanomagnet and a spin qubit as well as a network of nanomagnet-qubit-hybrids to engineer long-distance coupling of spin qubits using magnons as a quantum bus as well as Bose-Hubbard physics of magnons. We will also discuss that levitated magnets are extraordinary inertial and force sensors and that in a levitated nanomagnet the magnonic mode couples very strongly to internal elastic phonons, something that can be used for cavity quantum acoustomagnonics with potential applications for magnetic sensing.