Accelerated numerical algorithms for steady states of Gross-Pitaevskii equations coupled with microwaves

TL;DR

This paper introduces two new accelerated algorithms, ASGF and PPNCG, for efficiently computing steady states of coupled Gross-Pitaevskii equations with electromagnetic interactions, outperforming existing methods in benchmark tests.

Contribution

The paper develops two novel, accelerated numerical algorithms for steady states of nonlocal coupled GP equations, improving efficiency over prior methods.

Findings

PPNCG outperforms existing algorithms in benchmarks.

Both algorithms effectively compute vortex states.

Spectral discretization enhances computational accuracy.

Abstract

We present two accelerated numerical algorithms for single-component and binary Gross-Pitaevskii (GP) equations coupled with microwaves (electromagnetic fields) in steady state. One is based on a normalized gradient flow formulation, called the ASGF method, while the other on a perturbed, projected conjugate gradient approach for the nonlinear constrained optimization, called the PPNCG method. The coupled GP equations are nonlocal in space, describing pseudo-spinor Bose-Einstein condensates (BECs) interacting with an electromagnetic field. Our interest in this study is to develop efficient, iterative numerical methods for steady symmetric and central vortex states of the nonlocal GP equation systems. In the algorithms, the GP equations are discretized by a Legendre-Galerkin spectral method in a polar coordinate in two-dimensional (2D) space. The new algorithms are shown to outperform the existing ones through a host of benchmark examples, among which the PPNCG method performs the best. Additional numerical simulations of the central vortex states are provided to demonstrate the usefulness and efficiency of the new algorithms.