• BEC
• QCD
• simulazioni numeriche
• vortici

This thesis is dedicated to the study of two apparently different but closely related physical systems: vortex solutions arising in QCD at low temperature and ultra-high density on the one hand, and in Bose-Einstein condensates with multiple components of ultra-cold atoms on the other. In both physical systems, fractional vortices are nucleated in response to rotation, due to the superfluid nature of matter. Vortices in BEC condensates carry non-trivial circulation; in high density QCD they possess in addition non-Abelian color magnetic flux and ordinary magnetic flux, when electromagnetic effects are taken into account. These topological defects are considered in quark matter in the CFL phase, which has been proposed to be realized in the core of neutron stars. Particular attention is given to the modifications that the coupling with standard electromagnetism produces on the energy spectrum of elementary vortex solutions; also, the fate of vortices is considered when they reach the boundary of the CFL phase and connect with neutron and proton vortices in the npe phase. Considering rotating two-component BEC, which is also a focus of intense experimental and theoretical study today, the modifications on the vortex lattice induced by a tunable Rabi oscillations are investigated by numerical simulations. New vortex bound states are found and partner changing patterns are predicted to occur when the Rabi frequency is gradually increased. The structure of a vortex lattice is investigated for a three- component BEC, whose features are also relevant for the physics of vortex configurations in high-density QCD: the only possible structures are found to be the triangular Abrikosov lattice of fractional vortices and the vortex sheets, depending on the value of the inter- component coupling constant.