Quantization of magnetoelectric fields

Abstract

The effect of quantum coherence involving macroscopic degree of freedom, and occurring in systems far larger than individual atoms are one of the topical fields in modern physics. Because of material dispersion, a phenomenological approach to macroscopic quantum electrodynamics, where no canonical formulation is attempted, is used. The problem becomes more complicated when geometrical forms of a material structure have to be taken into consideration. Magnetic-dipolar-mode (MDM) oscillations in a magnetically saturated quasi-2D ferrite disk are macroscopically quantized states. In this ferrimagnetic structure, long-range dipole–dipole correlation in positions of electron spins can be treated in terms of collective excitations of a system as a whole. The near fields in the proximity of a MDM ferrite disk have space and time symmetry breakings. Such MDM-originated fields – called magnetoelectric (ME) fields – carry both spin and orbital angular momentums. By virtue of unique topology, ME fields are different from free-space electromagnetic (EM) fields. The ME fields are quantum fluctuations in vacuum. We call these quantized states ME photons. There are not virtual EM photons. We show that energy, spin and orbital angular momenta of MDM oscillations constitute the key physical quantities that characterize the ME-field configurations. We show that vacuum can induce a Casimir torque between a MDM ferrite disk, metal walls, and dielectric samples.