Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:1004.4581 · Physical Review A

Quantum demixing in binary mixtures of dipolar bosons

Piyush Jain, Massimo Boninsegni

Published Feb 7, 2011• 33 citations
arXivHTMLPDF

Abstract

Quantum Monte Carlo simulations of a two-component Bose mixture of trapped dipolar atoms of identical masses and dipole moments, provide numerical evidence of demixing at low finite temperatures. Demixing occurs as a consequence of quantum statistics, which results in an effective attraction between like bosons. Spatial separation of two components takes place at low temperature with the onset of long exchanges of identical particles, underlying Bose-Einstein condensation of both components. Conversely, at higher temperature the system is miscible due to the entropy of mixing. Exchanges are also found to enhance demixing in the case of mixtures of nonidentical and distinguishable species.

DOI
10.1103/physreva.83.023602

Related papers

Mixtures of Dipolar Gases in Two Dimensions: A Quantum Monte Carlo Study

Sergi Pradas, Jordi Boronat

We studied the miscibility of two dipolar quantum gases in the limit of zero temperature. The system under study is composed of a mixture of two Bose gases with dominant dipolar interaction in a two-dimensional harmonic confinement. The dipolar moments are all considered to be perpendicular to the plane, turning the dipolar potential in a purely repulsive and isotropic model. Our analysis is carried out by using the diffusion Monte Carlo method, which allows for an exact solution to the many-body problem within some statistical noise. Our results show that the miscibility between the two species is rather constrained as a function of the relative dipolar moments and masses of the two components. A narrow regime is predicted where both species mix and we introduce an adimensional parameter whose value quite accurately predicts the miscibility of the two dipolar gases.

arXiv:2112.11748•Condensed Matter•Apr 1, 2022•4 citations

Phase separation and temperature effects in mixture of two atomic species

Fabio Lingua

This thesis investigates bosonic mixtures in ultra-cold atom systems. We mainly focus on mixtures of two bosonic twin-species trapped in optical lattices, paying particular attention to the properties of spatial separation. The study is carried out by means of the path-integral quantum Monte Carlo by the two-worm algorithm and by analytical calculations where the complexity of the system allows it. The mixture is trapped in a square optical lattice at different filling and temperature conditions. We explore the ground-state phase diagram showing that various quantum phases can arise depending on the interplay between intra- and inter-species interactions. Demixed phases, characterized by spatial separation of the two species, are studied in details determining under which conditions they can be stabilized. The influence of temperature, filling factor and harmonic trap on phase separation is also investigated. An interesting dependence of the degree of demixing from temperature has been found, suggesting new ways to measure the temperature of a two-component bosonic mixture. We also study spatial phase separation in the simple case of a two-component mixture in a double-well potential both numerically and by means of the Bogoliubov approximaton. We show that even in this simple case the main features of the mixing/ demixing phase transitions are observed, and that the transition is characterized by a spectral collapse of the energy eigenvalues reflecting the dramatic change of algebraic structure of the model.

•Jan 1, 2017•0 citations

Demixing effects in mixtures of two bosonic species

Fabio Lingua, Marco Guglielmino, Vittorio Penna +1 more

Motivated by recent experiments on two-component systems, we investigate the ground-state phase diagram of a mixture of two bosonic species by means of path-integral quantum Monte Carlo simulations by a two-worm algorithm. The mixture is trapped in a square lattice at different filling conditions. Various quantum phases are stabilized depending on the interplay between intra- and interspecies interactions and on the filling factors. We show that the ground-state phase diagram at half-filling features a demixed superfluid phase and a demixed Mott-insulator phase when the interspecies interaction becomes greater than the intraspecies repulsion, and a double-superfluid phase or a supercounterflow otherwise. We show that demixing, characterized by spatial separation of the two species, can be detected experimentally through the effects of anisotropy revealed by time-of-flight images. We also study how demixing effects depend on the filling factor of the two components. Finally, we find that the supercounterflow phase is preserved in the presence of unbalanced populations.

arXiv:1507.08877•Physical Review A•Nov 13, 2015•42 citations

Dipolar condensed atomic mixtures and miscibility under rotation

Lauro Tomio, R. Kishor Kumar, A. Gammal

By considering symmetric- and asymmetric-dipolar coupled mixtures (with dysprosium and erbium isotopes), we report a study on relevant anisotropic effects, related to spatial separation and miscibility, due to dipole-dipole interactions (DDIs) in rotating binary dipolar Bose-Einstein condensates. The binary mixtures are kept in strong pancake-like traps, with repulsive two-body interactions modeled by an effective two-dimensional (2D) coupled Gross-Pitaevskii equation. The DDI are tuned from repulsive to attractive by varying the dipole polarization angle. A clear spatial separation is verified in the densities for attractive DDIs, being angular for symmetric mixtures and radial for asymmetric ones. Also relevant is the mass-imbalance sensibility observed by the vortex-patterns in symmetric- and asymmetric-dipolar mixtures. In an extension of this study, here we show how the rotational properties and spatial separation of these dipolar mixture are affected by a quartic term added to the harmonic trap of one of the components.

arXiv:1911.02734•SciPost Physics Proceedings•Feb 25, 2020•3 citations

Thermometry of bosonic mixtures in Optical Lattices via Demixing

Fabio Lingua, Barbara Capogrosso-Sansone, F. Minardi +1 more

Motivated by recent experiments and theoretical investigations on binary mixtures, we investigate the miscible-immiscible transition at finite temperature by means of Quantum Monte Carlo. Based on the observation that the segregated phase is strongly affected by temperature, we propose to use the degree of demixing for thermometry of a binary bosonic mixture trapped in an optical lattice. We show that the proposed method is especially sensitive at low temperatures, of the order of the tunnelling amplitude, and therefore is particularly suitable in the regime where quantum magnetism is expected.

arXiv:1609.08352•Scientific Reports•Jul 5, 2017•8 citations

Mixtures of ultracold Bose gases in one dimension: A Quantum Monte Carlo study

Parisi, Luca

In this thesis we investigate the properties of mixtures of Bose gases in one dimensions at zero temperature using quantum Monte-Carlo methods. First we investigate the limiting case of an impurity interacting with an atomic bath. We characterize the impurity, by calculating its effective mass, binding energy as well as the contact parameter between the impurity and the bath. In particular, we find that the effective mass rapidly increases to very large values when the impurity gets strongly coupled to an otherwise weakly repulsive bath. Then we describe uniform balanced mixtures with repulsive interactions. We investigate the miscibility phase diagram of the two components and find that correlations do not alter the phase diagram predicted by mean-field theories. We investigate the Andreev-Bashkin effect , a non-dissipative drag between the the two components of the gas and find that the drag becomes very large in the strongly interacting regime. In non-homogeneous systems we also investigate the frequency of the spin-dipole mode. Finally we describe mixtures with attractive inter-species interactions, where one can obtain a liquid ground state because of the competition between the inter-species attraction and intra-species repulsion. We characterize the the liquid and we find that the liquid state can be formed if the ratio of coupling strengths between inter-species attractive and intra-species repulsive interactions exceeds a critical value.

•Jan 1, 2019•0 citations
Quantum Monte Carlo simulations of a two-component Bose mixture of trapped dipolar atoms of identical masses and dipole moments, provide numerical evidence of demixing at low finite temperatures. Demixing occurs as a consequence of quantum statistics, which results in an effective attraction between like bosons. Spatial separation of two components takes place at low temperature with the onset of long exchanges of identical particles, underlying Bose-Einstein condensation of both components. Conversely, at higher temperature the system is miscible due to the entropy of mixing. Exchanges are also found to enhance demixing in the case of mixtures of nonidentical and distinguishable species.
We studied the miscibility of two dipolar quantum gases in the limit of zero temperature. The system under study is composed of a mixture of two Bose gases with dominant dipolar interaction in a two-dimensional harmonic confinement. The dipolar moments are all considered to be perpendicular to the plane, turning the dipolar potential in a purely repulsive and isotropic model. Our analysis is carried out by using the diffusion Monte Carlo method, which allows for an exact solution to the many-body problem within some statistical noise. Our results show that the miscibility between the two species is rather constrained as a function of the relative dipolar moments and masses of the two components. A narrow regime is predicted where both species mix and we introduce an adimensional parameter whose value quite accurately predicts the miscibility of the two dipolar gases.
This thesis investigates bosonic mixtures in ultra-cold atom systems. We mainly focus on mixtures of two bosonic twin-species trapped in optical lattices, paying particular attention to the properties of spatial separation. The study is carried out by means of the path-integral quantum Monte Carlo by the two-worm algorithm and by analytical calculations where the complexity of the system allows it. The mixture is trapped in a square optical lattice at different filling and temperature conditions. We explore the ground-state phase diagram showing that various quantum phases can arise depending on the interplay between intra- and inter-species interactions. Demixed phases, characterized by spatial separation of the two species, are studied in details determining under which conditions they can be stabilized. The influence of temperature, filling factor and harmonic trap on phase separation is also investigated. An interesting dependence of the degree of demixing from temperature has been found, suggesting new ways to measure the temperature of a two-component bosonic mixture. We also study spatial phase separation in the simple case of a two-component mixture in a double-well potential both numerically and by means of the Bogoliubov approximaton. We show that even in this simple case the main features of the mixing/ demixing phase transitions are observed, and that the transition is characterized by a spectral collapse of the energy eigenvalues reflecting the dramatic change of algebraic structure of the model.
Motivated by recent experiments on two-component systems, we investigate the ground-state phase diagram of a mixture of two bosonic species by means of path-integral quantum Monte Carlo simulations by a two-worm algorithm. The mixture is trapped in a square lattice at different filling conditions. Various quantum phases are stabilized depending on the interplay between intra- and interspecies interactions and on the filling factors. We show that the ground-state phase diagram at half-filling features a demixed superfluid phase and a demixed Mott-insulator phase when the interspecies interaction becomes greater than the intraspecies repulsion, and a double-superfluid phase or a supercounterflow otherwise. We show that demixing, characterized by spatial separation of the two species, can be detected experimentally through the effects of anisotropy revealed by time-of-flight images. We also study how demixing effects depend on the filling factor of the two components. Finally, we find that the supercounterflow phase is preserved in the presence of unbalanced populations.
By considering symmetric- and asymmetric-dipolar coupled mixtures (with dysprosium and erbium isotopes), we report a study on relevant anisotropic effects, related to spatial separation and miscibility, due to dipole-dipole interactions (DDIs) in rotating binary dipolar Bose-Einstein condensates. The binary mixtures are kept in strong pancake-like traps, with repulsive two-body interactions modeled by an effective two-dimensional (2D) coupled Gross-Pitaevskii equation. The DDI are tuned from repulsive to attractive by varying the dipole polarization angle. A clear spatial separation is verified in the densities for attractive DDIs, being angular for symmetric mixtures and radial for asymmetric ones. Also relevant is the mass-imbalance sensibility observed by the vortex-patterns in symmetric- and asymmetric-dipolar mixtures. In an extension of this study, here we show how the rotational properties and spatial separation of these dipolar mixture are affected by a quartic term added to the harmonic trap of one of the components.
Motivated by recent experiments and theoretical investigations on binary mixtures, we investigate the miscible-immiscible transition at finite temperature by means of Quantum Monte Carlo. Based on the observation that the segregated phase is strongly affected by temperature, we propose to use the degree of demixing for thermometry of a binary bosonic mixture trapped in an optical lattice. We show that the proposed method is especially sensitive at low temperatures, of the order of the tunnelling amplitude, and therefore is particularly suitable in the regime where quantum magnetism is expected.
In this thesis we investigate the properties of mixtures of Bose gases in one dimensions at zero temperature using quantum Monte-Carlo methods. First we investigate the limiting case of an impurity interacting with an atomic bath. We characterize the impurity, by calculating its effective mass, binding energy as well as the contact parameter between the impurity and the bath. In particular, we find that the effective mass rapidly increases to very large values when the impurity gets strongly coupled to an otherwise weakly repulsive bath. Then we describe uniform balanced mixtures with repulsive interactions. We investigate the miscibility phase diagram of the two components and find that correlations do not alter the phase diagram predicted by mean-field theories. We investigate the Andreev-Bashkin effect , a non-dissipative drag between the the two components of the gas and find that the drag becomes very large in the strongly interacting regime. In non-homogeneous systems we also investigate the frequency of the spin-dipole mode. Finally we describe mixtures with attractive inter-species interactions, where one can obtain a liquid ground state because of the competition between the inter-species attraction and intra-species repulsion. We characterize the the liquid and we find that the liquid state can be formed if the ratio of coupling strengths between inter-species attractive and intra-species repulsive interactions exceeds a critical value.