arXiv subjects

Zabardast Narzikulov

Publications and source records attributed to Zabardast Narzikulov.

4 recordsLinked to original sources

arXiv2022

The transition from Bose-Einstein condensate to supersolid states in Rydberg-dressed gases beyond Bogoliubov approximation

In this paper, we study Bose-Einstein condensation of Rydberg-dressed atoms considering finite range interactions. We use Hartree-Fock-Bogoliubov approximation based on Mean-Field approach. Moreover, within this approximation modified by the finite-range character of the two-body interaction we shall obtain analytical expressions for thermodynamic quantities of Rydberg-dressed Bose gas. The imaginary part of the quasiparticle spectrum of a BEC signals the instability of the roton mode with respect to the formation of supersolid state. Our theory predicts a second-order quantum phase transition from BEC to supersolid phase for Rydberg-dressed bosons in three dimensions.

cond-mat.quant-gas↗

arXiv2022

Self-consistent theory of a homogeneous binary Bose mixture with strong repulsive interspecies interaction

Multicomponent quantum gases are ideal platforms to study fundamental phenomena arising from the mutual interaction between different constituents. Particularly, due to the repulsive interactions between two species, the system may exhibit a phase separation. We develop a mean-field-based theory for a two-component Bose mixture, which is equivalent to the Hartree-Fock-Bogoliubov approximation, and derive analytical expressions for the phase boundary and miscibility. The majority of existing theories, which are valid only for weakly interacting Bose gases, predict that the phase boundary is determined by the criterion $g_{ab}\leqslant\sqrt{g_{aa} g_{bb}}$ (where $g_{ab}$ is a coupling constant between the components $a$ and $b$). We show that in the Bose-Einstein-condensation phase ($T\leqslant T_c$) the system may remain in a stable and miscible phase also for larger values of $g_{ab}$, depending on the gas parameter $γ$ and temperature.

cond-mat.quant-gas↗

arXiv2022

Defining a critical temperature of a crossover from BEC to the normal phase in anisotropic quantum magnets

We address the problem of identifying the critical temperature in a crossover from the Bose-Einstein condensed (BEC) phase to the normal phase. For this purpose we study the temperature dependence of magnetization of spin-gapped quantum magnets described by BEC of triplons. We have calculated the heat capacity $C_H$ at constant field and fluctuations in magnetization in a spin-gapped quantum magnet using the Hartree-Fock-Bogouliubov approximation and found optimized parameters of the Hamiltonian of triplon gas. In the region of phase transition, the heat capacity $C_H$ is smeared out due to the Dzyaloshinsky-Moriya (DM) interaction. The sharp maximum of the fluctuations in the magnetization is identified as the critical temperature of the crossover.

cond-mat.quant-gas↗

arXiv2018

Gr{ü}neisen parameter of quantum magnets with spin gap

Using Hartree-Fock-Bogoliubov (HFB) approach we obtained analytical expressions for thermodynamic quantities of the system of triplons in spin gapped quantum magnets such as magnetization, heat capacity and the magnetic Gr{ü}neisen parameter $Γ_H$. Near the critical temperature, $Γ_H$ is discontinuous and changes its sign upon the Bose-Einstein condensation (BEC) of triplons. On the other hand, in the widely used Hartree-Fock-Popov (HFP) approach there is no discontinuity neither in the heat capacity nor in the Gr{ü}neisen parameter. We predict that in the low-temperature limit and near the critical magnetic field $H_c$, $Γ_H$ diverges as $Γ_H\sim 1/T^{2}$, while it scales as $Γ_H\sim 1/(H-H_c)$ as the magnetic field approaches the quantum critical point at $H_c$.

cond-mat.quant-gas↗