Sørensen, Ole Søe3; Gammelmark, Søren3; Mølmer, Klaus3
1 Department of Physics and Astronomy, Science and Technology, Aarhus University2 Teoretisk naturvidenskab, Aarhus University, Aarhus University3 Department of Physics and Astronomy, Science and Technology, Aarhus University
We present first-principles numerical calculations for few-particle solutions of the attractive Bose-Hubbard model with periodic boundary conditions. We show that the low-energy many-body states found by numerical diagonalization can be written as translational superposition states of compact composite systems of particles. These compact states break the translational symmetry of the problem, and their center-of-mass and internal excitations offer simple explanations of the energy spectrum of the full model.
Physical Review a (atomic, Molecular and Optical Physics), 2012, Vol 85, Issue 4