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Q: Fachverband Quantenoptik und Photonik

Q 43: Ultracold Matter (Bosons) III (joint session Q/A)

Q 43.2: Vortrag

Mittwoch, 12. März 2025, 14:45–15:00, WP-HS

Coupled Higgs-Goldstone dynamics in the Bose-Hubbard model — •Thomas Hauschild¹, Ulli Pohl¹, Sayak Ray¹, and Johann Kroha^{1, 2} — ¹Physikalisches Institut, Universität Bonn, Nussallee 12, 53115 Bonn, Germany — ²School of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews KY16 9SS, United Kingdom

The realization of a Mott-superfluid transition in the Bose-Hubbard model using ultracold bosons in an optical lattice led to exploring many aspects of non-equilibrium physics over the past decade. These include collective excitations of the Bose-Einstein condensate near the Mott transition. We investigate the dynamics of these Higgs and Goldstone modes beyond the harmonic approximation using the field theory approach [1]. The coupling of the modes is analogous to the one in a Bosonic Josephson junction [2], and, thus, can possibly yield phase space dynamics like in a mathematical pendulum. In the long wavelength limit, we obtain the equations of motion for the coupled condensate amplitude and phase modes. In particular, we investigate the transition from a low-amplitude oscillation with spontaneously broken, localized phase to a running-phase mode.

[1] K. Sengupta, N. Dupuis, Phys. Rev. A, 71, 033629 (2005).

[2] A. Smerzi, S. Fantoni, S. Giovanazzi, S. R. Shenoy, Phys. Rev. Lett, 79, 4950 (1997).

Keywords: Bose-Hubbard model; Mott-Superfluid transition; Collective excitations; Higgs and Goldstone modes