arXiv subjects

V. Pastukhov

Publications and source records attributed to V. Pastukhov.

At least 19 recordsLinked to original sources

arXiv2026

Two- and three-body bound states in one-dimensional Fermi bipolaron with three-body interaction

We discuss the ground-state properties of two bosonic (or spin-1/2 fermionic in a singlet spin state) impurities immersed in a one-dimensional ideal Fermi gas with only the three-body contact interaction accounted for. Despite its simplicity, the considered model is found to demonstrate a variety of medium-induced few-body bound states. Particularly, using variational calculations with trial wave functions that correctly take into account one particle-hole excitation, we predict the emergence of a dimer state and several trimer states over a wide range of the three-body coupling parameter.

cond-mat.quant-gas↗

arXiv2026

Finite-temperature properties of low-dimensional bosons with three-body interaction

We discuss the finite-temperature properties of low-dimensional bosons with three-body interactions described by a Feshbach-resonance-like two-channel model. In particular, by using the approximate consideration that collects ring-like Feynman diagrams for the grand potential and resembles the three-body $t$-matrix approximation, we have computed the third virial coefficient, an equation of state, and the temperature depletion of the average number of closed-channel trimers. The calculated heat capacity demonstrates a non-monotonic temperature behavior, which is unusual for a low-dimensional Bose gas.

cond-mat.quant-gas↗

arXiv2025

One-dimensional tunneling of the two-body bound state

We consider bound and scattering states of the one-dimensional dimer formed by two coupled non-identical atoms when one of them also interacts with the zero-range potential located at the origin. By calculating the dimer localized and scattering wave functions, we identify properties of the system without the two-body bound-state collapse. In general, we predict an enhancement of the dimer reflection compared to a single atom, except for a narrow region on the attractive side of the external potential.

quant-ph↗

arXiv2025

Four-body physics in low-dimensional bosons with three-body interaction

The two-channel model for bosons with the three-body interaction is proposed. Similar to the Hamiltonian describing narrow Feshbach resonance in the two-body sector, our model includes the finite-range effects of the three-body potential and is well-defined in the ultraviolet (UV). A detailed exploration of the Efimov-like effect in the fractal-dimension system of four bosons is carried out. Peculiarities of the four-body bound states and the low-energy atom-trimer scattering in one dimension are revealed.

cond-mat.quant-gas↗

arXiv2025

Evolution of a single spin in ideal Bose gas at finite temperatures

We study the finite-temperature dynamics of non-interacting bosons with a single static spinful impurity immersed. A non-zero contact boson-impurity pairwise interaction is assumed only for the spin-up impurity state. By tracing out bosonic degrees of freedom, the exact time evolution of the impurity spin is calculated for pure and mixed initial ensembles of states. The time-dependent momentum distribution of bosons initially created in the Bose-condensed state and driven by the interaction with spin is analyzed.

cond-mat.quant-gas↗

arXiv2024

`Triviality' of universal relations for disordered systems

The universal relations for spin-$1/2$ fermions with contact interaction in the presence of quenched disorder are discussed. The disorder is modeled by a random external potential with the Gaussian distribution and $\delta$-like two-point correlation function. Utilizing simple scaling arguments, the renormalizability of the theory, and the Hellmann-Feynman theorem we identified the large-momentum tail of particle distribution and analog of Tan's energy relation for many-fermion systems with disorder in arbitrary dimension $d\ge 2$. It is shown that the energy-pressure relation manifests a kind of scale anomaly in two and three dimensions.

cond-mat.quant-gas↗

arXiv2024

Strongly interacting Bose-Fermi mixtures in $4-ε$ dimensions

Thermodynamically stable low-temperature phases of the Bose-Fermi mixtures composed of bosons and spinless fermions close to four dimensions are considered. In the regime, where the only boson-fermion two-body interaction is present and tuned to unitary limit, the properties of a system solely depend on the mass and number ratios of constituent atoms. In addition to the phase with the dimers (boson-fermion shallow bound states), we identified one more state of the mixture with the coexistence of fermionic dimers and trimers. The universal physics of these phases, the characteristic feature of is absence of the Bose-Einstein condensate, is discussed.

cond-mat.quant-gas↗

arXiv2024

Bipolaron in one-dimensional $SU(3)$ fermions with three-body interaction

The properties of the one-dimensional $SU(3)$ population-imbalanced fermions are discussed. The system is assumed to be in the two-body resonance where all two-body scattering lengths diverge, and the only interaction between fermions that is taken into account is the short-range three-body one. In particular, we consider the situation when only one `flavor' of fermions is macroscopically occupied, and there are exactly two atoms of two others. This system supports the trimer and the medium-induced dimer states studied here in detail and shows evidence of color superfluidity.

cond-mat.quant-gas↗

arXiv2024

Universal $p$-wave tetramers in low-dimensional fermionic systems with three-body interaction

Inspired by the narrow Feshbach resonance in systems with the two-body interaction, we propose the two-channel model of three-component fermions with the three-body interaction that takes into account the finite-range effects in low dimensions. Within this model, the $p$-wave Efimov-like effect in the four-body sector is predicted in fractional dimensions above 1D. The impact of the finite-range interaction on the formation of the four-body bound states in $d=1$ is also discussed in detail.

cond-mat.quant-gas↗

arXiv2023

Competition of superfluid phases in low-dimensional spin-$1\over 2$ fermions with $s$- and $p$-wave interactions

The ground state of spin-$1\over 2$ fermions with contact $s$-wave inter- and $p$-wave intra-species interactions is discussed. Particularly, we formulate the mean field scheme for calculating thermodynamic properties of the system in arbitrary dimension $D<2$ and discuss in detail the phase diagram in 1D case. Except clean phases with either singlet or triplet Cooper pairings, we have identified two mixed phases (one stable and another metastable) of the one-dimensional two-component fermions where both pairing mechanisms coexist.

cond-mat.quant-gas↗

arXiv2023

Trapped ideal Bose gas with a few heavy impurities

We formulate a general scheme for calculation of thermodynamic properties of ideal Bose gas with microscopic number of static impurities immersed, when the system is loaded in the harmonic trapping potential with quasi-1D and quasi-2D configurations. The binding energy of a single impurity and a detailed study of the medium-induced Casimir-like forces between two impurities in trapped Bose gas are numerically calculated in wide range of temperatures and interaction strengths.

cond-mat.quant-gas↗

arXiv2022

Second root of dilute Bose-Fermi mixtures

We discuss an equilibrium mean-field properties of mixtures consisting of bosons and spin-polarized fermionic atoms with a point-like interaction in an arbitrary dimension $2<d<4$. Particularly, we discuss except the standard weak-coupling limit of the system with slightly depleted Bose condensate and almost ideal Fermi gas, the (meta)stable phase with dimers composed exactly of one boson and one fermion. The peculiarities of the fermion-dimer and the boson-dimer three-body effective interactions and their impact on the thermodynamic stability of the dilute Bose-Fermi mixtures are elucidated.

cond-mat.quant-gas↗

arXiv2022

Efimov-like physics in fraction-dimensional Bose systems with three-body interaction

A few-body properties of spinless Bose particles interacting via the contact three-body potential in geometries with fractional dimensions $1<d<2$ are considered. In the four-body sector at three-body resonance we predict the existence of infinite tower of the Efimov bound states, and a similar behavior is found in the five-body problem. It is shown that a ratio of the high-energy levels in these two sectors is a universal constant. The consequences of emergence of the Efimov physics on the many-body behavior are briefly discussed.

cond-mat.quant-gas↗

arXiv2021

Polaron in almost ideal molecular Bose-Einstein condensate

We discuss properties of a single impurity atom immersed in the spin-$1/2$ dilute Fermi gas with equal populations of two species in the deep Bose-Einstein condensate (BEC) phase. In this limit, when an almost undepleted BEC of the tightly bound molecules of spin-up and spin-down fermions is formed, we calculate the parameters of an impurity spectrum. It is justified that the leading-order contribution to the impurity energy, while being determined by the two- and three-body scattering processes, is dominated by the former ones.

cond-mat.quant-gas↗

arXiv2021

Static impurities in a weakly-interacting Bose gas

We present a comprehensive discussion of the ground-state properties of dilute $D$-dimensional Bose gas interacting with a few static impurities. Assuming the short-ranged character of the boson-impurity interaction, we calculate the energy of three- and two-dimensional Bose systems with one and two impurities immersed.

cond-mat.quant-gas↗

arXiv2020

Impurity in a three-dimensional unitary Bose gas

By using simple and efficient method we discuss properties of a single impurity immersed in three-dimensional Bose gas with the interaction between particles tuned to unitary limit. Particularly, adopting the mean-field-like approximation we present the first estimations for the low-momentum parameters of the impurity spectrum, namely, the binding energy, the effective mass and the quasiparticle residue both for repulsive and attractive Bose polarons in the unitary gas.

cond-mat.quant-gas↗

arXiv2020

Two- and three-body effective potentials between impurities in ideal BEC

We exactly calculate the full temperature dependence of Casimir-like forces appearing between two and three static impurities loaded in the ideal Bose gas below the Bose-Einstein condensation transition point. Assuming the short-ranged character of the boson-impurity interaction, the calculation procedure presented here can be easily extended on a Bose system with an arbitrary number of impurities immersed.

cond-mat.quant-gas↗

arXiv2020

Mean-field study of repulsive 2D and 3D Bose polarons

The detailed mean-field treatment of the Bose polaron problem in two and three dimensions is presented. Particularly, assuming that impurity is immersed in the dilute Bose gas and interacts with bosons via the hard-sphere two-body potential, we calculate the low-momentum parameters of its spectrum, namely, the binding energy and the effective mass. The limits of applicability of the mean-field approach to a problem of mobile impurity in Bose-Einstein condensates are discussed by comparing our results to the Monte Carlo simulations data.

cond-mat.quant-gas↗