To the question of magnetism of quantum gases in equilibrium with radiation

The peculiarities of the influence of photonic component on the magnetic properties of a system of quantum gases in thermodynamic equilibrium with radiation in the presence of an external magnetic field are analyzed. The problem is not trivial, given that photons in a vacuum do not have a magnetic moment. It is assumed that the magnetic moment of photons is zero even in low-temperature gases. To study the announced question, a system of equations was constructed that describe the state of thermodynamic equilibrium of the specified medium. The solutions of these equations in analytical form were obtained in the temperature range far from the degeneracy temperatures of all components of the system. Both analytical and numerical methods were used to study the obtained solutions. The analysis of the solutions indicates a significant influence of photons and the intensity of the external magnetic field on the density distribution of all components of the medium, including the photonic one, and on the magnetic state of the medium. In particular, it is shown that an increase in the photon density in the system due to external sources leads to an increase in the characteristic of the inverse population of atomic levels. However, it was found that the magnetization of the system with an increase in the density of photons from external sources can both significantly increase and significantly decrease, depending on the quantum mechanical characteristics of the atomic states.