Dynamical properties of ultracold bosons in an optical lattice
- Theoretische Physik, ETH Zurich, CH-8093 Zurich (Switzerland)
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, 76100 (Israel)
- Institute for Quantum Optics and Quantum Information of the Austrian Academy of Science, 6020 Innsbruck (Austria)
We study the excitation spectrum of strongly correlated lattice bosons for the Mott-insulating phase and for the superfluid phase close to localization. Within a Schwinger-boson mean-field approach we find two gapped modes in the Mott insulator and the combination of a sound mode (Goldstone) and a gapped (Higgs) mode in the superfluid. To make our findings comparable with experimental results, we calculate the dynamic structure factor as well as the linear response to the optical lattice modulation introduced by Stoeferle et al. [Phys. Rev. Lett. 92, 130403 (2004)]. We find that the puzzling finite frequency absorption observed in the superfluid phase could be explained via the excitation of the gapped (Higgs) mode. We check the consistency of our results with an adapted f-sum rule and propose an extension of the experimental technique by Stoeferle et al. to further verify our findings.
- OSTI ID:
- 20976709
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Vol. 75, Issue 8; Other Information: DOI: 10.1103/PhysRevB.75.085106; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- English
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