Correlation effects and collective excitations in bosonic bilayers: Role of quantum statistics, superfluidity, and the dimerization transition

Filinov, A.

doi:10.1103/physreva.94.013603

Cited by 34 publications

(48 citation statements)

References 80 publications

(183 reference statements)

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“…For bosons (such as ultracold atoms, see, e.g., Refs. [97,98,99]) and boltzmannons (i.e., distinguishable particles [100,101]), P (X) is strictly positive and quasi-exact simulations of up to N ∼ 10 4 particles are possible [102,103]. For fermions (such as electrons, which we simulate in this work), on the other hand, P (X) can be both positive and negative and, thus, cannot be interpreted as a probability distribution.…”

Section: Path Integral Monte Carlomentioning

confidence: 91%

Ab initio path integral monte carlo simulation of the uniform electron gas in the high energy density regime

Dornheim

Moldabekov

Vorberger

et al. 2020

Plasma Phys. Control. Fusion

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The response of the uniform electron gas (UEG) to an external perturbation is of paramount importance for many applications. Recently, highly accurate results for the static density response function and the corresponding local field correction have been provided both for warm dense matter [J. Chem. Phys. 151, 194104 (2019)] and strongly coupled electron liquid [Phys. Rev. B 101, 045129 (2020)] conditions based on exact ab initio path integral Monte Carlo (PIMC) simulations. In the present work, we further complete our current description of the UEG by exploring the high energy density regime, which is relevant for, e.g., astrophysical applications and inertial confinement fusion experiments. To this end, we present extensive new PIMC results for the static density response in the range of 0.05 ≤ r s ≤ 0.5 and 0.85 ≤ θ ≤ 8. These data are subsequently used to benchmark the accuracy of the widely used random phase approximation and the dielectric theory by Singwi, Tosi, Land, and Sjölander (STLS). Moreover, we compare our results to configuration PIMC data where they are available and find perfect agreement with a relative accuracy of 0.001 − 0.01%. All PIMC data are available online.The Uniform Electron Gas in the High Density Regime 2 IntroductionThe uniform electron gas (UEG), also known as jellium or quantum one-component plasma, is defined as a system of Coulomb interacting electrons in a neutralizing homogeneous background and constitutes one of the most import model systems in physics and chemistry [1,2,3]. Having been introduced as a simple model description for conduction electrons in metals [4], the UEG exhibits a variety of interesting effects, such as Wigner crystallization [5,6,7] and a possible incipient excitonic mode which has been predicted to appear at low density [8,9,10,11].Moreover, the availability of highly accurate quantum Monte Carlo (QMC) data [12,13,14,15,16] at metallic densities and zero-temperature has sparked remarkable developments in many fields, most notably the hitherto unequaled success of density functional theory (DFT) regarding the description of real materials [17,18].Recently, the interest in matter under extreme conditions [19] has led to the need for analogous quantum Monte Carlo data at finite temperature. Of particular importance is the so-called warm dense matter (WDM) regime, which is defined by two characteristic parameters that are both of the order of one: i) the density parameter r s = r/a B (with r and a B being the average inter-particle distance and first Bohr radius) and ii) the reduced temperature θ = k B T /E F (with k B and E F being the Boltzmann constant and Fermi energy [1]), cf. Fig. 1 below. These conditions occur in astrophysical objects like giant planet interiors [20,21,22] and are expected to manifest on the pathway towards inertial confinement fusion [23]. Furthermore, WDM is nowadays routinely realized in large research facilities around the globe like the Linac Coherent Light Source (LCLS) [24], the National Ignition Facility (NIF) [25], and th...

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Section: Path Integral Monte Carlomentioning

confidence: 91%

Ab initio path integral monte carlo simulation of the uniform electron gas in the high energy density regime

Dornheim

Moldabekov

Vorberger

et al. 2020

Plasma Phys. Control. Fusion

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“…The ground state phase diagram of dipolar bosons in a 2D bilayer geometry (in continuous space) has been studied by Quantum Monte Carlo simulations [18,19] at low in-plane density, where no crystallization occurs. In this paper, we carry out a comprehensive study of the low temperature phase diagram of the system by means of Quantum Monte Carlo simulations.…”

Section: Introductionmentioning

confidence: 99%

Phases of dipolar bosons in a bilayer geometry

Cinti

Wang

2017

Phys. Rev. A

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We study by first principle computer simulations the low temperature phase diagram of bosonic dipolar gases in a bilayer geometry, as a function of the two control parameters, i.e., the in-plane density and the interlayer distance. We observe four distinct phases, namely paired and decoupled superfluids, as well as a crystal of dimers and one consisting of two aligned crystalline layers. A direct quantum phase transition from a dimer crystal to two independent superfluids is observed in a relatively wide range of parameters. No supersolid phase is predicted for this system.

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“…The reason is that dipoles of adjacent layers will form bound states which is not accounted for in the ansatz (4). For bilayers, the pairing effect has been well studied by quantum Monte Carlo simulations 22,23 and is not the subject of this work.…”

Section: Results For Dipolar Multilayers a Ground Statementioning

confidence: 99%

“…The ground state can be obtained, for example, from quantum Monte Carlo simulations. This provides exact ground state properties of dipolar quantum gases [22][23][24][38][39][40][41] , but it would be computationally very demanding for the large number of layers that we study in this work. For the fairly low partial denstities ρ α that we consider here, it is sufficient to use approximate methods.…”

Section: Correlated Basis Function Theorymentioning

confidence: 99%

“…But we note that the absence of rotons with a well-defined minimum is consistent with recent results for the excitations of dipolar bilayers obtained with quantum Monte Carlo simulations. 23,54 It was found that rotons appeared when dipoles form bound states (dimers), or if the density in each layer is so high that rotons are present due to the intralayer dipole-dipole repulsion, regardless of the interlayer coupling.…”

Section: B Dynamicsmentioning

confidence: 99%

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Multicomponent correlated-basis-function method and its application to multilayered dipolar Bose gases

2017

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We present a method for calculating the dynamics of a bosonic mixture, the multi-component correlated basis function (CBF) method. For single components, CBF results for the excitation energies agree quite well with experimental results, even for highly correlated systems like 4 He, and recent systematic improvements of CBF achieve perfect agreement. We give a full derivation of multi-component CBF, and apply the method to a dipolar Bose gas cut into two-dimensional layers by a deep optical lattice, with coupling between layers due to the long-ranged dipole-dipole interaction. We consider the case of strong coupling, leading to large positive interlayer correlations. We calculate the spectrum for a system of 8 layers and show that the strong coupling can lead to a simpler spectrum than in the uncoupled case, with a single peak carrying most of the spectral weight.

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Correlation effects and collective excitations in bosonic bilayers: Role of quantum statistics, superfluidity, and the dimerization transition

Cited by 34 publications

References 80 publications

Ab initio path integral monte carlo simulation of the uniform electron gas in the high energy density regime

Ab initio path integral monte carlo simulation of the uniform electron gas in the high energy density regime

Phases of dipolar bosons in a bilayer geometry

Multicomponent correlated-basis-function method and its application to multilayered dipolar Bose gases

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