Global and local condensate and superfluid fraction of a few hard core bosons in a cubic optical lattice plus external harmonic confinement
arXiv:1106.0324 · doi:10.1140/epjd/e2012-30371-2
Abstract
We explore the global and local condensate and superfluid (SF) fractions in a system of a few hard core (HC) bosons (N=8 and N=40) trapped inside a combined harmonic optical cubic lattice (CHOCL) at T=0 K. The condensate fraction (CF) is computed for individual lattice wells by separating the one-body density matrix (OBDM) of the whole system into components at the various lattice sites. Then each "lattice-site" component is diagonalized to find its eigenvalues. The eigenvalues are obtained by a method presented earlier [Dubois and Glyde, Phys. Rev. A {\bf 63}, 023602 (2001)]. The effects of interference between the condensates in the lattice wells on the CF in one well is also investigated. The SF fraction (SFF) is calculated for N=40 by using the diffusion formula of Pollock and Ceperley [Pollock and Ceperley, Phys. Rev. B {\bf 36}, 8343 (1987)]. Our chief result is an opposing behavior of the global CF and SFF with increasing lattice wave vector . In addition, the CF in a lattice well is enhanced by the interference with its neighbor wells beyond the result when the interference is neglected. The global SF is depleted with a rise of the repulsion between the bosons, yet at very strong interaction superfluidity is still present. The global CF remains almost constant with increasing HC repulsion. A reduction in the lattice dimension, i.e. an increase in the lattice wave vector, increases the local CF in each lattice well, but reduces the corresponding local SFF. At large HC repulsion, a coexisting SF-(vacuum)MI phase is established.
The tables in the previous withdrawn version (v2) have been corrected and the article updated. This is the final version which has been submitted to Phys. Rev. A
References in corpus (20)
- Single Particle Tunneling in Strongly Driven Double Well Potentials
- Experimental demonstration of single-site addressability in a two-dimensional optical lattice
- Few-boson dynamics in double wells: From single-atom to correlated-pair tunneling
- Condensate fraction in a 2D Bose gas measured across the Mott-insulator transition
- Phase Coherence and Superfluid-Insulator Transition in a Disordered Bose-Einstein Condensate
- Number squeezing, quantum fluctuations and oscillations in mesoscopic Bose Josephson junctions
- Tunneling dynamics of few bosons in a double well
- Finite temperature study of bosons in a two dimensional optical lattice
- Superfluid to Mott-insulator transition of hardcore bosons in a superlattice
- Bosonic superfluid-insulator transition in continuous space
- Effect of interactions on harmonically confined Bose-Fermi mixtures in optical lattices
- Theoretical description of two ultracold atoms in finite 3D optical lattices using realistic interatomic interaction potentials
- Finite temperature theory of superfluid bosons in optical lattices
- Localization and delocalization of ultracold bosonic atoms in finite optical lattices
- Signatures of the superfluid to Mott insulator transition in cold bosonic atoms in a one dimensional optical lattice
- Condensate fraction of cold gases in non-uniform external potential
- Superfluidity versus localization in bulk 4He at zero temperature
- Finite temperature coherence of the ideal Bose gas in an optical lattice
- Josephson physics mediated by the Mott insulating phase
- Bose condensation of interacting gases in traps with and without optical lattice