2014/03/31 by Luca Barbiero, L. Barbiero, M. Abad +2
Physics and Astronomy · #Bose–Hubbard model #Cold Atom Physics and Bose-Einstein Condensates #Condensed matter physics #Density matrix renormalization group #Ferromagnetism #Hamiltonian (control theory) #Hubbard model #Ising model #Mean field theory #Mott insulator #Mott transition #Optical lattice #Paramagnetism #Phase transition #Physics #Quantum #Quantum fluctuation #Quantum many-body systems #Quantum mechanics #Quantum phase transition #Renormalization group #Strong Light-Matter Interactions #Superconductivity #Superfluidity #cond-mat.quant-gas
paper · pdf · doi:10.1103/physreva.93.033645
published as Phys. Rev. A 93, 033645 (2016) · 6 pages, 3 figures
openalex publication_date 2016/03/25 · arxiv created 2016/03/27 · arxiv updated 2016/03/29 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We describe the ground state of a gas of bosonic atoms with two coherently coupled internal levels in a deep optical lattice in a one-dimensional geometry. In the single-band approximation this system is described by a Bose-Hubbard Hamiltonian. The system has a superfluid and a Mott insulating phase that can be either paramagnetic or ferromagnetic. We characterize the quantum phase transitions at unit filling by means of a density-matrix renormalization-group technique and compare the results with a mean-field approach and an effective spin Hamiltonian. The presence of the ferromagnetic Ising-like transition modifies the Mott lobes. In the Mott insulating region the system maps to the ferromagnetic spin-1/2 XXZ model in a transverse field and the numerical results compare very well with the analytical results obtained from the spin model. In the superfluid regime quantum fluctuations strongly modify the phase transition with respect to the well-established mean-field three-dimensional classical bifurcation.