5 papers
Standard basis operator method for ground-state and temperature properties of single and two-component Bose-Hubbard model
Oliwier Urbański, Tomasz P. Polak
We formulate an improved standard basis operator (SBO) method for the single and two-component Bose-Hubbard model in three dimensions. In the first case, nonzero temperature predic…
Quantum phase transition in transverse-field Ising model on Sierpiński gasket lattice
Tymoteusz Braciszewski, Oliwier Urbański, Piotr Tomczak
We investigate the quantum phase transition in the transverse-field Ising model on the Sierpiński gasket using finite-size scaling (FSS) and numerical renormalization group (NRG).…
Resolving problems with the continuum limit in coherent-state path integrals
Oliwier Urbański
The paper solves the problem of continuum limit in bosonic thermal coherent-state path integrals. For this purpose, exact discrete versions of the path integral are constructed for…
Exploring the variational method for thermodynamic models
Oliwier Urbański
This work explores the possibilities of the Gibbs-Bogoliubov-Feynman variational method, aiming at finding room for designing various drawing schemes. For example, mean-field appro…
An infinite grid of mesoscopic resistors: investigation and visualization of ballistic conduction
Oliwier Urbański
A square lattice of mesoscopic resistors is considered. Each bond is modeled as a narrow waveguide, while junctions are sources of elastic scattering given by a scattering matrix \…