Many-body Bose systems and the hard-sphere model: dynamic properties from the weak to the strong interaction regime

Year: 2014

Authors: Rota R., Tramonto F., Galli D.E., Giorgini S.

Autors Affiliation: Dipartimento di Fisica and INO-CNR BEC Center, Università degli Studi di Trento, via Sommarive 14, 38123 Trento, Italy; Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16, 20134 Milano, Italy

Abstract: We obtain ab-initio estimations of the dynamic structure factor, S(q, omega), of Bose gases at zero temperature. More precisely, we use the Genetic Inversion via Falsification of Theories (GIFT) algorithm to perform analytic continuations of imaginary time correlation functions computed via an exact Path Integral projector method. Using the hard-sphere potential to model the two-body interactions between the atoms, we compute S(q,.) changing the gas parameter from the dilute regime (na(3) = 10(-4)) up to the density corresponding to superfluid He-4 at equilibrium (na(3) = 0.2138). With increasing density, we observe the emergence of a broad multiphonon contribution accompanying the quasiparticle peak and a crossover of the dispersion of elementary excitations from a Bogoliubov-like spectrum to a phonon-maxon-roton curve. Apart from the low wave vector region, for na(3) = 0.2138 the energy-momentum dispersion relation and the static density response function, chi(q), turns out to be in good agreement with the superfluid He-4 experimental data at equilibrium density.


Volume: 529      Pages from: 012022  to: 012022

KeyWords: ultracold gases
DOI: 10.1088/1742-6596/529/1/012022

Citations: 3
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