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Information × Registration Number 0222U003349, 0121U108722 , R & D reports Title Development of the methods of statistical physics and quantum field theory for study of the problems of multiparticle quantum systems and induced gravitation and gauge fields in the theory of (super)strings and branes popup.stage_title Head Sliusarenko Yurii V., д.ф.-м.н. Registration Date 08-03-2022 Organization National Science Center "Kharkiv Institute of Physics and Technology" popup.description2  From the first principles of quantum statistical mechanics there has been developed a microscopic approach for description of many-particle system of interacting atoms with spin 1. In the framework of the developed approach it was shown that the spin of atom induces, except for conventional magnetization vector, additional parameters of description related to quadrupole degrees of freedom. There have been constructed many-particle Hamiltonians with different symmetry that take into account interaction of internal degrees of freedom. The Hamiltonian with SU(3) symmetry that includes 3 spin and 5 quadrupole operators has been applied to study ferromagnetic and quadrupole phases of weakly interacting Bose-gas of atoms with spin 1 in the presence of the Bose-Einstein condensate. It was shown that among various phase states ferromagnetic state is characterized by the lowest energy and its thermodynamic characteristics such as sound velocity, single-particle excitations get essentially modified as compared with those calculated using "conventional" Hamiltonian with bilinear term in the spin operators. It was proved that for non-local potentials it is necessary to take into account quadrupole degrees of freedom, which are not essential when the interaction is parametrized by the scattering lengths. Besides it was shown that upon parametrization of interaction by the scattering length it is impossible to reveal full spectrum of single-particle excitations. Obtained results open novel perspectives for study of various properties of quantum gases with higher-spin structural units at low and utralow temperatures. Product Description popup.authors Bulakhov Mykyta S. Peletminskyi Serhii V. Peletmynskyi Oleksandr S. Slyusarenko Yurii V. Sotnikov Andrii H. Uvarov Dmytro V. popup.nrat_date 2022-03-09 Close