Novel superfluid states in bosonic systems
In my dissertation, I will discuss unconventional superfluid states of various bosonic systems and present benchmark calculations for phase diagrams. The method of study is based on quantum Monte Carlo simulations by the Worm algorithm. The two qualitatively different systems to be discussed in the thesis are: (i) superfluidity of lower dimensional objects, i.e dislocations and defects, embedded in solid structures both in optical lattices and in realistic systems such as 4He. (ii) the two-component Bose-Hubbard model. Besides the interesting phases and phase diagrams that they exhibit, bosonic optical lattice systems are also interesting for studies of quantum magnetism where under certain conditions they can be mapped onto various spin Hamiltonians. On the other hand, superfluid dislocations in 4He is an important and interesting subject for it’s relevance to supersolid behavior observed in solid 4 He. I will also present technical details of the path integral Monte Carlo and the Worm algorithm and generalization of the algorithm to the two-component bosonic systems.