Speaker
Description
We investigate dilute Bose-Bose mixtures confined in an external harmonic potential that squeezes them in one spatial direction towards the two-dimensional limit, extending a recent study by some of the co-authors [1] by investigating rotating droplets which host vortices.
Specifically, we examine a quantum droplet composed of two hyperfine states of 39K potassium atoms, utilizing Mean-Field and Lee-Huang-Yang interaction density functionals. We solve the extended Gross-Pitaevskii equation in the rotating frame of reference using imaginary time evolution to determine energies and density profiles. The stability of droplets is further confirmed by real-time evolution. Our analysis focuses on identifying the critical number of atoms required at which a central vortex becomes the ground state, for different magnetic fields, confinement strengths, and angular velocities. Additionally, we explore the optimal vorticity distribution across the mixture components for different atom numbers and angular velocities.
We find that the critical number of atoms needed to form a stable vortex decreases with the increase of squeezing. Through our investigation, we have discovered that for larger droplets and faster rotations, the vortex configuration maximizing angular momentum is favoured, while in smaller or slowly rotating droplets – where vortices are usually excited states – interactions become more significant.
[1] A. Sanuy, et al., PRA 109, 013313 (2024).
