Vortices in attractive Bose-Einstein condensates in two dimensions.

Area of Science:

• Quantum physics
• Atomic physics
• Condensed matter physics

Background:

• Bose-Einstein condensates (BECs) are quantum states of matter.
• Vortices are topological defects in superfluids.
• Attractive interactions in BECs lead to different phenomena than repulsive ones.

Purpose of the Study:

• To elucidate the form and stability of quantum vortices in BECs with attractive atomic interactions.
• To investigate the properties of these vortices as generalizations of Townes solitons.
• To explore the existence of radially excited states in such systems.

Main Methods:

• Theoretical analysis of the Gross-Pitaevskii equation for attractive BECs.
• Investigation of stationary states and their stability properties.
• Examination of vortex solutions in confined geometries.

Main Results:

• Quantum vortices in attractive BECs manifest as ring bright solitons.
• These solitons generalize the Townes soliton to non-zero winding numbers (m).
• An infinite sequence of radially excited stationary states, characterized by concentric matter-wave rings and nodes, exists for each m.
• Both stable and unstable regimes for these vortices can be achieved in confined geometries.

Conclusions:

• The study elucidates the nature of quantum vortices in attractive Bose-Einstein condensates.
• Radially excited states, distinct from those in repulsive condensates, are predicted.
• The findings suggest that these vortices and their excited states are experimentally observable in 2D attractive BECs.