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arXiv:1906.05605 · Physical Review A

Collective excitations and tunneling dynamics in long bosonic Josephson junctions

M. R. Momme, Y. M. Bidasyuk, Michael Weyrauch

Published Sep 3, 2019• 10 citations
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Abstract

We investigate the low-energy dynamics of two coupled anisotropic Bose-Einstein condensates forming a long Josephson junction. The theoretical study is performed in the framework of the two-dimensional Gross-Pitaevskii equation and the Bogoliubov--de Gennes formalism. We analyze the excitation spectrum of the coupled Bose condensates and show how low-energy excitations of the condensates lead to multiple-frequency oscillations of the atomic populations in the two wells. This analysis generalizes the standard bosonic Josephson equation approach. We also develop a one-dimensional hydrodynamic model of the coupled condensates, that is capable of reproducing the excitation spectrum and population dynamics of the system.

DOI
10.1103/physreva.100.033601

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The Josephson effect can be observed in a Bose-Einstein condensate in a double-well potential, which is attributed to the tunneling of bosons between two wells. We propose a multi-mode theory to investigate the dynamics of local excitations in a one-dimensional condensate in a double-well potential. We show that the system can be described by two independent two-mode models. The Josephson oscillation and the self-trapping of local collective excitations are predicted analytically and confirmed by numerical simulation.
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