Impurities in a Bose-Einstein condensate using quantum Monte-Carlo methods: ground-state properties.

In this thesis we investigate the properties of impurities immersed in a dilute Bose gas at zero temperature using quantum Monte-Carlo methods. The interactions between bosons are modeled by a hard sphere potential with scattering length a, whereas the interactions between the impurity and the bosons are modeled by a short-range, square-well potential where both the sign and the strength of the scattering length b can be varied by adjusting the well depth. We calculate the binding energy, the effective mass and the pair correlation functions of a impurity along the attractive and the repulsive polaron branch. In particular, at the unitary limit of the impurity-bosons interaction, we find that the binding energy is much larger than the chemical potential of the bath signaling that many bosons dress the impurity thereby lowering its energy and increasing its effective mass. We characterize this state by calculating the bosons-boson pair correlation function and by investigating the dependence of the binding energy on the gas parameter of the bosonic bath. We also investigate the ground-state properties of M impurities in a Bose gas at T=0. In particular, the energy and the phase diagram by using both quantum Monte-Carlo and mean field methods.

Grantor dc:publisher

Università degli studi di Trento

Year dc:date

2015

Author dc:creator

• Peña Ardila, Luis A.

Contributors dc:contributor

• Giorgini, Stefano

• Settore FIS/02 - Fisica Teorica, Modelli e Metodi Matematici
• Settore FIS/03 - Fisica della Materia

Statement dc:rights

• info:eu-repo/semantics/openAccess
• license:Tutti i diritti riservati (All rights reserved)

Language dc:language

eng

Identifier

http://dx.doi.org/10.15168/11572_369010
10.15168/11572_369010

OAI identifier oai:identifier

oai:iris.unitn.it:11572/369010