On-site number statistics of ultracold lattice bosons

Abstract

We study on-site occupation number fluctuations in a system of interacting bosons in an optical lattice. The ground-state distribution is obtained analytically in the limiting cases of strong and weak interaction, and by means of exact Monte Carlo simulations in the strongly correlated regime. As the interaction is increased, the distribution evolves from Poissonian in the non-interacting gas to a sharply peaked distribution in the Mott-insulator (MI) regime. In the special case of large occupation numbers, we demonstrate analytically and check numerically that there exists a wide interval of interaction strength, in which the on-site number fluctuations remain Gaussian and are gradually squeezed until they are of order unity near the superfluid (SF)-MI transition. Recently, the on-site number statistics were studied experimentally in a wide range of lattice potential depths [Phys. Rev. Lett. \textbf{96}, 090401 (2006)]. In our simulations, we are able to directly reproduce experimental conditions using temperature as the only free parameter. Pronounced temperature dependence suggests that measurements of on-site atom number fluctuations can be employed as a reliable method of thermometry in both SF and MI regimes.

9 pages, 4 figures

References in corpus (8)

• Localization of bosonic atoms by fermionic impurities in a 3d optical lattice
• Imaging the Mott Insulator Shells using Atomic Clock Shifts
• Formation of spatial shell structures in the superfluid to Mott insulator transition
• Coherent collisional spin dynamics in optical lattices
• Interference pattern and visibility of a Mott insulator
• Signatures of the superfluid to Mott-insulator transition in the excitation spectrum of ultracold atoms
• Finite-temperature effects on the number fluctuation of ultracold atoms across the Superfluid to Mott-insulator transition
• A Scanning Electron Microscope for Ultracold Atoms

Cited by in corpus (5)

• Effective Action Approach for Quantum Phase Transitions in Bosonic Lattices
• Photon and polariton fluctuations in arrays of QED-cavities
• Finite temperature coherence of the ideal Bose gas in an optical lattice
• Density correlations in ultracold Fermi systems within the exact Richardson solution
• Cooling ultracold bosons in optical lattices by spectral transform