Rabi-Josephson oscillations and self-trapped dynamics in atomic junctions with two bosonic species

TL;DR

This paper explores the complex dynamics of two-component Bose-Einstein condensates in a double-well potential, revealing various oscillation regimes and comparing reduced Hamiltonian models with direct GPE simulations.

Contribution

It introduces a four-degree-of-freedom Hamiltonian model to describe diverse dynamical behaviors in two-component BECs and validates it against direct GPE simulations.

Findings

Identification of regular Josephson and mixed Rabi-Josephson oscillations.

Observation of self-trapping regimes in the system.

Validation of the reduced Hamiltonian model with GPE simulations.

Abstract

We investigate the dynamics of two-component Bose-Einstein condensates (BECs), composed of atoms in two distinct hyperfine states, which are linearly coupled by two-photon Raman transitions. The condensate is loaded into a double-well potential (DWP). A variety of dynamical behaviors, ranging from regular Josephson oscillations, to mixed Rabi-Josephson oscillations and to regimes featuring an increasing complexity, are described in terms of a reduced Hamiltonian system with four degrees of freedoms, which are the numbers of atoms in each component in the left and right potential wells, whose canonically conjugate variables are phases of the corresponding wave functions. Using the system with the four degrees of freedom, we study the dynamics of fractional imbalances of the two bosonic components, and compare the results to direct simulations of the Gross-Pitaevskii equations (GPEs) describing the bosonic mixture. We perform this analysis when the fractional imbalance oscillates around a zero-time averaged value and in the self-trapping regime as well.