Data di Pubblicazione:
2013
Citazione:
Quantum Monte Carlo study of dynamic properties of ultracold gases / D.E. Galli. ((Intervento presentato al convegno Correlations in ultracold atomic systems tenutosi a Padova nel 2013.
Abstract:
We investigate the dynamic structure factor of a system of Bose particles at zero temperature using quantum
Monte Carlo methods. Interactions are modeled using a hard-sphere potential of size a and simulations are
performed for values of the gas parameter na3 ranging from the dilute regime up to densities n where the
thermodynamically stable phase is a solid. With increasing density, we observe a crossover of the dispersion of
elementary excitations from a Bogoliubov-type spectrum to a phonon-maxon-roton curve and the emergence of
a broad multiphonon contribution accompanying the single-quasiparticle peak. In particular, for na3 = 0.2138,
which corresponds to superfluid 4He at equilibrium density, the extracted spectrum turns out to be in good
agreement with the experimental energy-momentum dispersion relation in the roton region and for higher
momenta. The behavior of the spectral function at the same density in the stable solid and metastable gas phase
above the freezing point is also discussed.
Tipologia IRIS:
14 - Intervento a convegno non pubblicato
Elenco autori:
D.E. Galli
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