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Karina K. Jimenez Garcia, Yu-Ju Lin, James V. Porto, Ian B. Spielman
Abstract
Ultra-cold atoms in optical lattices realize essential models in condensed matter physics. Like with most experiments with ultra-cold atoms, our Rubidium-87 Bose Einstein condensate is confined in a harmonic trapping potential that persists even when loaded into an optical lattice. Here we realize the 2D Bose-Hubbard Hamiltonian and focus on the effects of the trapping term, not present in bulk condensed matter systems. By measuring condensate fraction we identify the transition from superfluid to insulator as a function of atom density and lattice depth. Our results are in excellent agreement with the Quantum Monte Carlo universal state diagram suitable for the trapped systems introduced by Rigol et. al. (Phys. Rev. A 79, 053605 (2009)).
Jimenez, K.
, Lin, Y.
, Porto, J.
and Spielman, I.
(2010),
Phases of a 2D Bose Gas in an Optical Lattice, Physical Review Letters, [online], https://doi.org/10.1103/PhysRevLett.105.110401
(Accessed October 14, 2025)