Signatures of the superfluid to Mott-insulator transition in the excitation spectrum of ultracold atoms

Abstract

We present a detailed analysis of the dynamical response of ultra-cold bosonic atoms in a one-dimensional optical lattice subjected to a periodic modulation of the lattice depth. Following the experimental realization by Stoferle et al [Phys. Rev. Lett. 92, 130403 (2004)] we study the excitation spectrum of the system as revealed by the response of the total energy as a function of the modulation frequency Omega. By using the Time Evolving Block Decimation algorithm, we are able to simulate one-dimensional systems comparable in size to those in the experiment, with harmonic trapping and across many lattice depths ranging from the Mott-insulator to the superfluid regime. Our results produce many of the features seen in the experiment, namely a broad response in the superfluid regime, and narrow discrete resonances in the Mott-insulator regime. We identify several signatures of the superfluid-Mott insulator transition that are manifested in the spectrum as it evolves from one limit to the other.

18 pages and 12 figures; Some improved results and additional references. To appear in a special issue of New J. Phys

References in corpus (3)

• Real time evolution using the density matrix renormalization group
• Bose-Fermi Mixtures in a Three-dimensional Optical Lattice
• Localization of bosonic atoms by fermionic impurities in a 3d optical lattice

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• Dynamical simulations of classical stochastic systems using matrix product states
• On-site number statistics of ultracold lattice bosons
• Many-body Landau-Zener tunneling in the Bose-Hubbard model
• Effective spin model for interband transport in a Wannier-Stark lattice system
• Fast initialization of a high-fidelity quantum register using optical superlattices
• Response of Bose gases in time-dependent optical superlattices
• Ultracold Bose gases in time-dependent 1D superlattices: response and quasimomentum structure
• Bose-Einstein condensates in disordered potentials