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DY: Fachverband Dynamik und Statistische Physik
DY 35: Poster: Quantum Dynamics and Many-body Systems
DY 35.7: Poster
Wednesday, March 20, 2024, 15:00–18:00, Poster D
revealing quantum effects in bosonic Josephson junctions: a multi-configuration atomic coherent state approach — •Yulong Qiao1 and Frank Grossman2 — 1Institute for theoretical physics, TU Dresden, 01062 Dresden, Germany — 2Institute for theoretical physics, TU Dresden, 01062 Dresden, Germany
The bosonic Josephson junction can be effectively described by a two-site Bose-Hubbard model. Many quantum phenomena in this model result from the dynamic interplay between the particle imbalance and the relative phase between two sites, which are treated as a pair of conjugated variables in mean-field theory. However, some nontrivial quantum effects such as the self-trapping effect and spontaneous symmetry breaking are described incorrectly by mean-field results [1].
We have developed a new variational approach utilizing a set of generalized coherent states to study the non-equilibrium dynamics of the Bose-Hubbard model [2]. Here, we apply this method to the bosonic Josephson junction and demonstrate that quantum effects beyond the mean-field approximation are easily uncovered by only a few basis functions [3]. Specifically, for the case of plasma oscillations, just two basis states already gives a good qualitative agreement with numerically exact quantum solutions. In order to correctly account for macroscopic quantum self-trapping, moderately more basis states are needed.
[1] Y. Qiao and F. Grossmann, Phys. Rev. A 103, 042209 (2021). [2] S. Wimberger, G Manganelli, A Brollo, L Salasnich, Phys. Rev. A 103, 023326 (2021) [3] Y. Qiao and F. Grossmann, Front. in Phys., 11:1221614 (2023)
Keywords: bosonic Josephson junction; atomic coherent state; variational principle; time-dependent Schrödinger equation; multiconfiguration ansatz