# The effects of trap-confinement and interatomic interactions on Josephson effects and macroscopic quantum self-trapping for a Bose-Einstein Condensate

## TL;DR

This paper theoretically investigates how trap geometry and different interatomic interactions influence Josephson oscillations and self-trapping phenomena in a Bose-Einstein condensate confined in a double-well potential, revealing control over quantum states.

## Contribution

It introduces a comprehensive analysis of trap aspect ratio effects on JO and MQST across contact, dipolar, and finite-range interactions in BECs, highlighting new transition mechanisms.

## Key findings

- Trap aspect ratio controls transition between JO and MQST for contact interactions.
- Dipolar interactions exhibit regime transitions by changing trap geometry and orientation.
- Finite-range effects enable JO and MQST even with large scattering lengths near Feshbach resonances.

## Abstract

We theoretically study the effects of trap-confinement and interatomic interactions on Josephson oscillations (JO) and macroscopic quantum self-trapping (MQST) for a Bose-Einstein condensate (BEC) confined in a trap which has a symmetric double-well (DW) potential along z-axis and 2D harmonic potentials along x- and y-axis. We consider three types of model interaction potentials: contact, long-range dipolar and finite-range potentials. Our results show that by changing the aspect ratio between the axial and radial trap sizes, one can induce a transition from JO to MQST for contact interactions with a small scattering length. For long-range dipolar interatomic interactions, we analyze transition from Rabi to Josephson regime and Josephson to MQST regime by changing the aspect ratio of the trap for a particular dipolar orientation. For a finite-range interaction, we study the effects of relatively large scattering length and effective range on JO and MQST. We show that JO and MQST are possible even if scattering length is relatively large, particularly near a narrow Feshbach resonance due to the finite-range effects.