Spectral weight redistribution in strongly correlated bosons in optical lattices

Abstract

We calculate the single-particle spectral function for the one-band Bose-Hubbard model within the random phase approximation (RPA). In the strongly correlated superfluid, in addition to the gapless phonon excitations, we find extra gapped modes which become particularly relevant near the superfluid-Mott quantum phase transition (QPT). The strength in one of the gapped modes, a precursor of the Mott phase, grows as the QPT is approached and evolves into a hole (particle) excitation in the Mott insulator depending on whether the chemical potential is above (below) the tip of the lobe. The sound velocity of the Goldstone modes remains finite when the transition is approached at a constant density, otherwise, it vanishes at the transition. It agrees well with Bogoliubov theory except close to the transition. We also calculate the spatial correlations for bosons in an inhomogeneous trapping potential creating alternating shells of Mott insulator and superfluid. Finally, we discuss the capability of the RPA approximation to correctly account for quantum fluctuations in the vicinity of the QPT.

14 pages, 12 figures

References in corpus (14)

• Quantum Magnets under Pressure: Controlling Elementary Excitations in TlCuCl3
• Quantum Fluctuations in the Superfluid State of the BCS-BEC Crossover
• Quantum Monte Carlo simulations of confined bosonic atoms in optical lattices
• Formation of spatial shell structures in the superfluid to Mott insulator transition
• Mott insulator to superfluid transition in the Bose-Hubbard model: a strong-coupling approach
• Dynamical properties of ultracold bosons in an optical lattice
• Interference pattern and visibility of a Mott insulator
• Bose-Einstein condensates in 1D optical lattices: compressibility, Bloch bands and elementary excitations
• Criterion for bosonic superfluidity in an optical lattice
• The Amplitude Mode in the Quantum Phase Model
• Interacting Bose gases in quasi-one dimensional optical lattices
• Deconfinement in a 2D optical lattice of coupled 1D boson systems
• Perturbative corrections to the Gutzwiller mean-field solution of the Mott-Hubbard model
• Ultracold Fermi gases in the BEC-BCS crossover: a review from the Innsbruck perspective

Cited by in corpus (5)

• Exploring correlated 1D Bose gases from the superfluid to the Mott-insulator state by inelastic light scattering
• Strong coupling theory for the Jaynes-Cummings-Hubbard model
• Strong-coupling expansion for the momentum distribution of the Bose Hubbard model with benchmarking against exact numerical results
• Excitation spectra of strongly correlated lattice bosons and polaritons
• Superfluid to Mott-insulator transition of cold atoms in optical lattices