Two-dimensional quantum droplets in dipolar Bose gases

Boudjemâa, Abdelâali

doi:10.1088/1367-2630/ab3fc7

Cited by 23 publications

(14 citation statements)

References 53 publications

(122 reference statements)

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“…Increasing further the temperature (T > T c ), the free en- ergy increases without any special structure and thus, the self-bound state loses its peculiar self-evaporation phenomenon and entirely destroys eventually. The same situation takes place for dipolar droplets in a single BEC [53][54][55] and in dual condensates [29,49]. Note that T c strongly relies on ǫ 0 and hence, on the interspecies interactions as we shall see below.…”

Section: Finite-temperature Casementioning

confidence: 67%

Many-body and temperature effects in two-dimensional quantum droplets in Bose-Bose mixtures

Boudjemaa

2021

Preprint

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We study the equilibrium properties of self-bound droplets in two-dimensional Bose mixtures employing the time-dependent Hartree-Fock-Bogoliubov theory. This theory allows one to understand both the many-body and temperature effects beyond the Lee-Huang-Yang description. We calculate higher-order corrections to the excitations, the sound velocity, and the energy of the droplet. Our results for the ground-state energy are compared with the diffusion Monte Carlo data and good agreement is found. The behavior of the depletion and anomalous density of the droplet is also discussed. At finite temperature, we show that the droplet emerges at temperatures well below the Berezinskii-Kosterlitz-Thouless transition temperature. The critical temperature strongly depends on the interspecies interactions. Our study is extended to the finite size droplet by numerically solving the generalized finite-temperature Gross-Pitaevskii equation which is obtained self-consistently from our formalism in the framework of the local density approximation.

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Section: Finite-temperature Casementioning

confidence: 67%

Many-body and temperature effects in two-dimensional quantum droplets in Bose-Bose mixtures

Boudjemaa

2021

Preprint

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“…( 1)-( 4). The numerical simulation was performed using the split-step Fourier transform and the convolution method to remove the singularity of the DDI at the origin [22,42]. Once the stability is checked we proceed with the cylindrical symmetry in order to compute the normal and anomalous exchange contributions (for more details see Ref.…”

Section: Resultsmentioning

confidence: 99%

“…Recently, dipolar self-bound droplets have been the object of intense theoretical investigations [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. Many of the results coming from these studies, such as groundstate properties, lifetimes, and excitation frequencies of the droplet, are based on the zero-temperature generalized Gross-Pitaevskii (GGP) equation, which includes the Lee-Huang-Yang (LHY) corrections [2,3,[9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Quantum correlations in dipolar droplets: Time-dependent Hartree-Fock-Bogoliubov theory

Boudjemaa,

Guebli

2020

Preprint

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We investigate the effects of quantum correlations on dipolar quantum droplets. To this end, we derive self-consistent time-dependent Hartree-Fock-Bogoliubov equations that fairly describe the dynamics of the order parameter, the normal, and anomalous quantum correlations of the droplet. We analyze the density profiles, the critical number of particles, the condensate depletion, and the pair correlation function. Our predictions are compared with very recent experimental and Quantum Monte-Carlo simulations results and excellent agreement is found.

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“…From Equations (4) and (2), the two body interaction potential becomes [ 25 ]

V_{2 D} (\overset{k}{true}) = g_{2 D} (1 - C \vec{k})

where

C = \frac{2 π d^{2}}{g_{2 normalD}}

. The polarization bubble in Equation (1) is given by [ 26 ]

Π (i ω, \vec{k}) = \frac{1}{β} \sum_{n} \int \frac{d^{2} q}{{(2 π)}^{2}} ℑ_{0} (i ω + i ω_{n}, \vec{k} + \vec{q}) ℑ_{0} (i ω_{n}, \vec{q})

where

β = 1 / k_{normalB} T

( k B and T are the Boltzmann constant and temperature respectively),

ω_{n} = \frac{2 n π}{β}

are the Matsubara bosonic frequencies, and the noninteraction Green's function in momentum‐frequency space is [ 27 ]

ℑ_{0} (i ω_{n}, q) = \frac{1}{i ω_{n} - ξ_{normalq}}

…”

Section: Formulationmentioning

confidence: 99%

Effects of Thermally Induced Roton‐Like Excitation on the Superfluid Density of a Quasi‐2D Dipolar Bose Condensed Gas

Yavari

Forouharmanesh

2020

Annalen der Physik

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Using the Green's function approach, the density–density correlation function and the dielectric function in the random‐phase approximation for a quasi‐two‐dimensional (quasi‐2D) dipolar Bose gas are derived. From the pole of the density correlation function, by considering thermally induced roton‐like excitations, the excitation spectrum of the system is calculated. It is shown that the position and depth of the roton minimum of the excitation spectrum are tunable by changing the temperature. To show how the position of the roton minimum influences the phenomenon of superfluidity, the superfluid density of the system is obtained and it is shown that the interplay of the thermal rotonization, contact and dipole–dipole interaction (DDI) can affect the superfluid fraction of a quasi‐2D Bose gas. It is found that contact, DDI interactions, and thermally induced rotons enhance the fluctuations and reduce the superfluid density. In the absence of DDI and thermally induced rotons, the usual T3 dependence of superfluid density in 2D is obtained and the correction T4 term arises from DDI. It is shown that if the roton minimum is close to zero, the thermally induced rotons change the linear temperature dependence of the superfluid fraction, leading to a transition to nontrivial supersolid phase.

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Two-dimensional quantum droplets in dipolar Bose gases

Cited by 23 publications

References 53 publications

Many-body and temperature effects in two-dimensional quantum droplets in Bose-Bose mixtures

Many-body and temperature effects in two-dimensional quantum droplets in Bose-Bose mixtures

Quantum correlations in dipolar droplets: Time-dependent Hartree-Fock-Bogoliubov theory

Effects of Thermally Induced Roton‐Like Excitation on the Superfluid Density of a Quasi‐2D Dipolar Bose Condensed Gas

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