Quantum swapping of immiscible Bose-Einstein condensates as an alternative to the Rayleigh-Taylor instability

TL;DR

This paper investigates how two immiscible Bose-Einstein condensates can swap positions via quantum interpenetration under strong magnetic forces, offering a quantum alternative to classical Rayleigh-Taylor instability.

Contribution

It introduces the concept of quantum swapping of condensates as an alternative to classical fluid instabilities, supported by numerical and analytical models.

Findings

Quantum swapping occurs with strong magnetic forces.

Development of modulational instability leads to quasi-turbulence.

Quantum interpenetration has no classical analogue.

Abstract

We consider a two-component Bose-Einstein condensate in a quasi-one-dimensional harmonic trap, where the immiscible components are pressed against each other by an external magnetic force. The zero-temperature non-stationary Gross-Pitaevskii equations are solved numerically; analytical models are developed for the key steps in the process. We demonstrate that if the magnetic force is strong enough, then the condensates may swap their places in the trap due to dynamic quantum interpenetration of the nonlinear matter waves. The swapping is accompanied by development of a modulational instability leading to quasi-turbulent excitations. Unlike the multidimensional Rayleigh-Taylor instability in a similar geometry of two-component quantum fluid systems, quantum interpenetration has no classical analogue. A crossover between the Rayleigh-Taylor instability and the quantum interpenetration in a two-dimensional geometry is demonstrated.