Polarons in a ferromagnetic spinor Bose-Einstein condensates

TL;DR

This paper studies polarons in a ferromagnetic spinor Bose-Einstein condensate, calculating their energies and effective masses across different interaction regimes, and discusses a transition to self-trapping with experimental implications.

Contribution

It provides analytical and variational methods to analyze polaron properties in a spinor BEC, including a transition from mobile to self-trapped states, which is a novel insight.

Findings

Calculated polaron energies and effective masses in weak and strong coupling regimes.

Identified a transition from mobile to self-trapped polarons in strong coupling.

Estimated experimental signatures of polaron effects in spinor BECs.

Abstract

We investigate the polarons formed by immersing a spinor impurity in a ferromagnetic state of $F=1$ spinor Bose-Einstein condensate. The ground state energies and effective masses of the polarons are calculated in both weak-coupling regime and strong-coupling regime. In the weakly interacting regime the second order perturbation theory is performed. In the strong coupling regime we use a simple variational treatment. The analytical approximations to the energy and effective mass of the polarons are constructed. Especially, a transition from the mobile state to the self-trapping state of the polaron in the strong coupling regime is discussed. We also estimate the signatures of polaron effects in spinor BEC for the future experiments.