Títol:
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The inverse-square interaction phase diagram: unitarity in the bosonic ground state
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Autor/a:
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Astrakharchik, Grigori; Kryuchkov, P. S.; Kurbakov, I. L.; Lozovik, Yu. E.
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Altres autors:
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Universitat Politècnica de Catalunya. Departament de Física; Universitat Politècnica de Catalunya. SIMCON - First-principles approaches to condensed matter physics: quantum effects and complexity |
Abstract:
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Ground-state properties of bosons interacting via inverse square potential (three dimensional Calogero-Sutherland model) are analyzed. A number of quantities scale with the density and can be naturally expressed in units of the Fermi energy and Fermi momentum multiplied by a dimensionless constant (Bertsch parameter). Two analytical approaches are developed: the Bogoliubov theory for weak and the harmonic approximation (HA) for strong interactions. Diffusion Monte Carlo method is used to obtain the ground-state properties in a non-perturbative manner. We report the dependence of the Bertsch parameter on the interaction strength and construct a Padé approximant which fits the numerical data and reproduces correctly the asymptotic limits of weak and strong interactions. We find good agreement with beyond-mean field theory for the energy and the condensate fraction. The pair distribution function and the static structure factor are reported for a number of characteristic interactions. We demonstrate that the system experiences a gas-solid phase transition as a function of the dimensionless interaction strength. A peculiarity of the system is that by changing the density it is not possible to induce the phase transition. We show that the low-lying excitation spectrum contains plasmons in both phases, in agreement with the Bogoliubov and HA theories. Finally, we argue that this model can be interpreted as a realization of the unitary limit of a Bose system with the advantage that the system stays in the genuine ground state contrarily to the metastable state realized in experiments with short-range Bose gases. |
Matèries:
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-Àrees temàtiques de la UPC::Física -Phase transformations (Statistical physics) -Plasmons (Physics) -unitarity -gas-solid phase transition -plasmons -Bogoliubov theory -harmonic approximation theory -diffusion Monte Carlo method -Transformacions de fase (Física estadística) -Plasmons (Física) -Monte Carlo method -Montecarlo, Mètode de |
Drets:
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Attribution-NonCommercial-NoDerivs 3.0 Spain
http://creativecommons.org/licenses/by-nc-nd/3.0/es/ |
Tipus de document:
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Article - Versió publicada Article |
Publicat per:
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Multidisciplinary Digital Publishing Institute (MDPI)
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