Finite-temperature effects on the number fluctuation of ultracold atoms across the Superfluid to Mott-insulator transition

TL;DR

This paper investigates how finite temperature influences number fluctuations in ultracold Bose atoms across the superfluid to Mott-insulator transition, using numerical methods to match experimental observations.

Contribution

It introduces a numerical approach to analyze finite-temperature effects in the Bose-Hubbard model, improving understanding of experimental data near the phase transition.

Findings

Finite-temperature phase diagram of the homogeneous Bose-Hubbard model.

Finite-temperature effects improve the fit to experimental number fluctuation data.

Non-negligible temperature effects are present in current experiments.

Abstract

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. \textbf{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.