Slave-particle approach to the finite-temperature properties of ultracold Bose gases in optical lattices

Journal Article · Sat Apr 15 04:00:00 EDT 2006 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.73.0· OSTI ID:20787142

Xiancong, Lu; Yue, Yu ^[1]; Jinbin, Li ^[2]

---

1. Institute of Theoretical Physics, Chinese Academy of Sciences, P.O. Box 2735, Beijing 100080 (China)
2. Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China)

By using slave particle (slave boson and slave fermion) techniques on the Bose-Hubbard model, we study the finite temperature properties of ultracold Bose gases in optical lattices. The phase diagrams at finite temperature are depicted by including different types of slave particles and the effect of the finite types of slave particles is estimated. The superfluid density is evaluated using the Landau second order phase transition theory. The atom density, excitation spectrum, and dispersion curve are also computed at various temperatures, and how the Mott-insulator evolves as the temperature increases is demonstrated. For most quantities to be calculated, we find that there are no qualitative differences in using the slave boson or the slave fermion approaches. However, when studying the stability of the mean field state, we find that in contrast to the slave fermion approach, the slave boson mean field state is not stable. Although the slave boson mean field theory gives a qualitatively correct phase boundary, it corresponds to a local maximum of Landau free energy and cannot describe the second order phase transition because the coefficient a{sub 4} of the fourth order term is always negative in the free energy expansion.

• OSTI ID: 20787142
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 4 Vol. 73; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
ABSORPTION SPECTRA
ATOMS
BOSE-EINSTEIN GAS
BOSONS
DENSITY
EXCITATION
EXPANSION
FERMIONS
FREE ENERGY
HUBBARD MODEL
MEAN-FIELD THEORY
PHASE DIAGRAMS
PHASE TRANSFORMATIONS
STABILITY
SUPERFLUIDITY