Modified dynamics of weakly coupled BEC's Josephson Junction (BJJ)

TL;DR

This paper introduces a modified model for the tunneling dynamics of weakly coupled Bose-Einstein condensates in a Josephson Junction, accounting for an equilibrium condition that prevents macroscopic quantum self-trapping and aligns oscillation frequency with Josephson energy.

Contribution

It proposes a new modified dynamical equation for BJJ that avoids MQST and confirms oscillation frequency dependence on Josephson energy, supported by numerical analysis.

Findings

Stationary states exist in both symmetric and asymmetric BJJs.

MQST is automatically avoided in the modified model.

Oscillation frequency depends solely on Josephson energy, confirmed experimentally.

Abstract

The tunnelling quantum dynamics of bimodal BJJ system is modified through introducing an equilibrium condition, which is based on the assumption that the BJJ is tend to keep on its ground state (with a lowest energy) during the oscillation. The tunnelling dynamics of BJJ with symmetric and asymmetric traps is discussed through numerically solving the modified equations. Stationary states are found to exist in the both BJJs. Compared to previous works, the macroscopic quantum self trapping (MQST) is auto-avoided. Meanwhile, it is revealed that the BJJ oscillates with its inherent frequency which is only related to the Josephson energy, which has been testified experimentally in other contexts.