Equilibrium vortex formation in ultrarapidly rotating two-component Bose-Einstein condensates

TL;DR

This paper theoretically investigates vortex formation in ultrafast rotating two-component Bose-Einstein condensates, analyzing equilibrium structures, stability, and vortex configurations across different phases and rotation speeds.

Contribution

It introduces a combined numerical scheme to ensure equilibrium states and derives a critical rotation frequency for vortex structure transitions in binary condensates.

Findings

Identification of a critical rotation frequency  for vortex structure changes

Analysis of vortex configurations in different phase separations

Demonstration of stability conditions with added quartic trapping potential

Abstract

Equilibrium vortex formation in rotating binary Bose gases with a rotating frequency higher than the harmonic trapping frequency is investigated theoretically. We consider the system being evaporatively cooled to form condensates and a combined numerical scheme is applied to ensure the binary system being in an authentic equilibrium state. To keep the system stable against the large centrifugal force of ultrafast rotation, a quartic trapping potential is added to the existing harmonic part. Using the Thomas-Fermi approximation, a critical rotating frequency \Omega_c is derived, which characterizes the structure with or without a central density hole. Vortex structures are studied in detail with rotation frequency both above and below ?\Omega_c and with respect to the miscible, symmetrically separated, and asymmetrically separated phases in their nonrotating ground-state counterparts.