Impurity induced Modulational instability in Bose-Einstein condensates

TL;DR

This paper investigates how impurities induce and influence modulational instability in Bose-Einstein condensates using linear stability analysis and numerical simulations, revealing impurity effects on stability and soliton dynamics.

Contribution

It provides a detailed analysis of impurity effects on modulational instability in BECs, highlighting how impurity fraction and interaction strength affect stability and soliton dissipation.

Findings

Impurities can induce MI in otherwise stable BECs.

Higher impurity fraction and stronger coupling increase MI tendency.

Impurities reduce soliton lifetime through dissipation.

Abstract

By means of linear stability analysis (LSA) and direct numerical simulations of the coupled Gross-Pitaevskii(GP)equations, we address the impurity induced modulational instability (MI) and the associated nonlinear dynamics in Bose-Einstein condensates (BECs). We explore the dual role played by the impurities within the BECs -- the instigation of MI and the dissipation of the initially generated solitary waves. Because of the impurities, the repulsive BECs are even modulationally unstable and this tendency towards MI increases with increasing impurity fraction and superfluid-impurity coupling strength. However, the tendency of a given BEC towards the MI decreases with the decreasing mass of the impurity atoms while the sign of the superfluid-impurity interaction plays no role. The above results are true even for attractive BECs except for a weak superfluid-impurity coupling, where the MI phenomenon is marginally suppressed by the presence of impurities. The dissipation of the solitons reduces their lifetime and is eminent for a larger impurity fraction and strong superfluid-impurity strength respectively.