Nonlinear management of the miscibility-immiscibility transition in binary Bose-Einstein condensates

TL;DR

This paper explores how nonlinear management techniques can control the transition between mixed and separated phases in two-component Bose-Einstein condensates, revealing stable domain-wall structures and the effects of periodic interaction variation.

Contribution

It introduces a novel application of nonlinearity management to control the miscibility-immiscibility transition in binary BECs, including analytical and numerical analysis of domain walls and stability.

Findings

Stable domain-wall solutions identified and matched analytically and numerically.

Nonlinearity management can restrict the miscibility by crossing the transition periodically.

Rabi coupling shifts the critical interaction strength for phase separation.

Abstract

We investigate application of the nonlinearity management (NM, i.e., periodic variation of the strength of the inter-component repulsion) to the miscibility-immiscibility (MIM) transition across the critical point of a two-component BEC, both with and without the linear mixing (Rabi coupling, RC) between the components. To this end, we first identify, by means of a variational approximation and numerical solution, diverse stationary domain-wall (DW) structures supported by the system in the absence of the management. The approximate analytical solutions for the DWs are found to be in excellent agreement with their numerical counterparts. An analytical estimate is also produced for the upshift of the MIM transition caused by the pressure of the trapping potential in the case of a confined system. An exact DW solution is produced for the system including the P\"{o}schl-Teller potential, which is stable (unstable) if the potential is repulsive (attractive). Further, we find the spectrum of linear excitations in the spatially uniform mixed state, and thus establish parameter regions where the system is stable/unstable against demixing. In particular, RC upshifts the critical strength of the inter-component repulsion for the onset of the MIM transition. Eigenfrequencies of excitations on top of DW states are identified from numerical simulations through monitoring the evolution of perturbed states. Weak NM applied at the DW eigenfrequency reveals features of the nonlinear resonance. Stronger NM, under which the system periodically crosses the MIM-transition point, restricts the miscibility.