Màster Oficial en Física Avançada, , Facultat de Física, Universitat de Barcelona, Curs: 2015, Tutors: Bruno Juliá-Díaz i Artur Polls
This work contains a detailed analysis of the properties of the ground state of a
two-component two-sites Bose-Hubbard model, which captures the physics of a binary mixture of
Bose-Einstein condensates trapped in a double-well potential. The atom-atom interactions within
each species and among the two species are taken as variable parameters while the hopping terms are
kept fixed. To characterize the ground state we use observables such as the imbalance of population
and its quantum uncertainty. The quantum many-body correlations present in the system are further
quantified by studying the degree of condensation of each species, and the entanglement between the
two species. The latter is measured by means of the Schmidt gap, the von Neumann entropy or the
purity obtained after tracing out a part of the system. A number of relevant states are identified,
e.g. Schrödinger catlike many-body states, in which the outcome of the population imbalance of
both components is completely correlated, and other states with even larger von Neumann entropy
which have a large spread in Fock space