Anomalous tunneling of collective excitations and effects of superflow in the polar phase of a spin-1 spinor Bose-Einstein condensate

TL;DR

This paper studies how collective excitations in a polar phase spin-1 Bose-Einstein condensate tunnel through barriers, revealing perfect transmission at low energies and unique behaviors under superflow and critical current conditions.

Contribution

It demonstrates that gapless modes in the polar phase exhibit anomalous tunneling behaviors, including perfect transmission, even with superflow, and clarifies conditions where reflection occurs.

Findings

Goldstone modes show perfect low-energy transmission

Superflow does not affect tunneling except at critical current

Spin-wave transmission persists unless interaction strengths are equal

Abstract

We investigate tunneling properties of collective modes in the polar phase of a spin-1 spinor Bose-Einstein condensate. This spinor BEC state has two kinds of gapless modes, i.e., Bogoliubov mode and spin-wave. Within the framework of the mean-field theory at T=0, we show that these Goldstone modes exhibit the perfect transmission in the low-energy limit. Their anomalous tunneling behaviors still hold in the presence of superflow, except in the critical current state. In the critical current state, while the tunneling of Bogoliubov mode is accompanied by finite reflection, the spin-wave still exhibit the perfect transmission, unless the strengths of a spin-dependent and spin-independent interactions take the same value.