skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Effects of finite temperature on the Mott-insulator state

Abstract

We investigate the effects of finite temperature on ultracold Bose atoms confined in an optical lattice plus a parabolic potential in the Mott-insulator state. In particular, we analyze the temperature dependence of the density distribution of atomic pairs in the lattice, by means of exact Monte Carlo simulations. We introduce a simple model that quantitatively accounts for the computed pair density distributions at low enough temperatures. We suggest that the temperature dependence of the atomic pair statistics may be used to estimate the system's temperature at energies of the order of the atoms' interaction energy.

Authors:
 [1];  [2];  [3];  [1];  [4];  [5]
  1. National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)
  2. (United States)
  3. (Austria)
  4. Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003 (United States)
  5. (Russian Federation)
Publication Date:
OSTI Identifier:
20786737
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. A; Journal Volume: 73; Journal Issue: 1; Other Information: DOI: 10.1103/PhysRevA.73.013408; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; 46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; ATOMS; BOSE-EINSTEIN STATISTICS; COMPUTERIZED SIMULATION; DENSITY; DISTRIBUTION; MONTE CARLO METHOD; PHOTON-ATOM COLLISIONS; POTENTIALS; TEMPERATURE DEPENDENCE

Citation Formats

Pupillo, Guido, Department of Physics, University of Maryland, College Park, Maryland 20742, Institute for Quantum Optics and Quantum Information, 6020 Innsbruck, Williams, Carl J., Prokof'ev, Nikolay V., and Russian Research Center 'Kurchatov Institute', 123182, Moscow. Effects of finite temperature on the Mott-insulator state. United States: N. p., 2006. Web. doi:10.1103/PHYSREVA.73.0.
Pupillo, Guido, Department of Physics, University of Maryland, College Park, Maryland 20742, Institute for Quantum Optics and Quantum Information, 6020 Innsbruck, Williams, Carl J., Prokof'ev, Nikolay V., & Russian Research Center 'Kurchatov Institute', 123182, Moscow. Effects of finite temperature on the Mott-insulator state. United States. doi:10.1103/PHYSREVA.73.0.
Pupillo, Guido, Department of Physics, University of Maryland, College Park, Maryland 20742, Institute for Quantum Optics and Quantum Information, 6020 Innsbruck, Williams, Carl J., Prokof'ev, Nikolay V., and Russian Research Center 'Kurchatov Institute', 123182, Moscow. Sun . "Effects of finite temperature on the Mott-insulator state". United States. doi:10.1103/PHYSREVA.73.0.
@article{osti_20786737,
title = {Effects of finite temperature on the Mott-insulator state},
author = {Pupillo, Guido and Department of Physics, University of Maryland, College Park, Maryland 20742 and Institute for Quantum Optics and Quantum Information, 6020 Innsbruck and Williams, Carl J. and Prokof'ev, Nikolay V. and Russian Research Center 'Kurchatov Institute', 123182, Moscow},
abstractNote = {We investigate the effects of finite temperature on ultracold Bose atoms confined in an optical lattice plus a parabolic potential in the Mott-insulator state. In particular, we analyze the temperature dependence of the density distribution of atomic pairs in the lattice, by means of exact Monte Carlo simulations. We introduce a simple model that quantitatively accounts for the computed pair density distributions at low enough temperatures. We suggest that the temperature dependence of the atomic pair statistics may be used to estimate the system's temperature at energies of the order of the atoms' interaction energy.},
doi = {10.1103/PHYSREVA.73.0},
journal = {Physical Review. A},
number = 1,
volume = 73,
place = {United States},
year = {Sun Jan 15 00:00:00 EST 2006},
month = {Sun Jan 15 00:00:00 EST 2006}
}
  • We study the thermodynamics of ultracold Bose atoms in optical lattices by numerically diagonalizing the mean-field Hamiltonian of the Bose-Hubbard model. This method well describes the behavior of long-range correlations and therefore is valid deep in the superfluid phase. For the homogeneous Bose-Hubbard model, we draw the finite-temperature phase diagram and calculate the superfluid density at unity filling. We evaluate the finite-temperature effects in a recent experiment probing number fluctuation [Phys. Rev. Lett. 96 090401 (2006)], and find that our finite-temperature curves give a better fitting to the experimental data, implying non-negligible temperature effects in this experiment.
  • We study the Mott insulator-superfluid transition in a two-band boson Hubbard model, which can be mapped onto a spin-1/2 XY model with spins coupled to an additional Ising degree of freedom. By using a modified mean field theory that includes the effects of phase fluctuations, we show that the transition is first order at both zero and finite temperatures. On the Mott insulator side, there may be reentrance in phase transition. These features are consequences of the underlying transition between competing defect poor and defect rich phases. The possible relevance of the model and our results to supersolid {sup 4}Hemore » and cold bosonic atoms in optical lattices are discussed.« less
  • We investigate the existence of quantum quasi-phase-transitions for an ensemble of ultracold bosons in a one-dimensional optical lattice performing exact diagonalizations of the Bose-Hubbard Hamiltonian. When an external parabolic potential is added to the system quasi-phase-transitions are induced by the competition of on-site mean-field energy, hopping energy, and energy offset among lattice sites due to the external potential and lead to the coexistence of regions of particle localization and delocalization in the lattice. We clarify the microscopic mechanisms responsible for these quasi-phase-transitions as a function of the depth of the external potential when the on-site mean-field energy is large comparedmore » to the hopping energy. In particular, we show that a model Hamiltonian involving a few Fock states can describe the behavior of energy gap, mean particle numbers per site, and number fluctuations per site almost quantitatively. The role of symmetry on the gap as a function of the depth of the external trapping potential is elucidated. We discuss possible experimental signatures of quasi-phase-transitions studying the single-particle density matrix and explain microscopically the occurrence of local maxima in the momentum distribution. The role of a thermal population of the excited states on the momentum distribution is discussed.« less
  • We study two models realized by two-component Fermi gases loaded in optical lattices. We clarify that multiband effects inevitably caused by the optical lattices generate a rich structure, when the systems crossover from the region of weakly bound molecular bosons to the region of strongly bound atomic bosons. Here the crossover can be controlled by attractive fermion interaction. One of the present models is a case with attractive fermion interaction, where an insulator-superfluid transition takes place. The transition is characterized as the transition between a band insulator and a Bose-Einstein condensate superfluid state. Differing from the conventional Bardeen-Cooper-Schrieffer (BCS) superfluidmore » transition, this transition shows unconventional properties. In contrast to the one-particle excitation gap scaled by the superfluid order parameter in the conventional BCS transition, because of the multiband effects, a large gap of one-particle density of states is retained all through the transition, although the superfluid order grows continuously from zero. A re-entrant transition with lowering temperature is another unconventionality. The other model is the case with coexisting attractive and repulsive interactions. Within a mean-field treatment, we find a new insulating state, an orbital ordered insulator. This insulator is one candidate for the Mott insulator of molecular bosons and is the first example that the orbital internal degrees of freedom of molecular bosons appears explicitly. Besides the emergence of a new phase, a coexisting phase also appears where superfluidity and an orbital order coexist just by doping holes or particles. The insulating and superfluid particles show differentiation in momentum space as in the high-T{sub c} cuprate superconductors.« less
  • Electronic and structural properties of the high-pressure phase of Fe{sub 2}O {sub 3} were determined by combining the methods of M{umlt o}ssbauer spectroscopy, x-ray diffraction, and electrical resistance, R(P,thinspT) , to 80thinspthinspGPa. Because of a first-order phase transition taking place in the 50{endash}75thinspthinspGPa range and accompanied by a volume decrease of {approximately}10{percent} , a breakdown of the electronic d-d correlation occurred, leading to a Mott transition, a metallic and a nonmagnetic single Fe{sup 3+} electronic state. The high-pressure structure is of the distorted Rh{sub 2}O {sub 3}- II type. The accommodation of the denser phase within this six-coordinated structure ismore » attributable to the metallic state. {copyright} {ital 1999} {ital The American Physical Society}« less