Controlled creation and decay of singly-quantized vortices in a polar magnetic phase

Quantized vortices appear in physical systems from superfluids and superconductors to liquid crystals and high energy physics. Unlike their scalar cousins, superfluids with complex internal structure can exhibit rich dynamics of decay and even fractional vorticity. Here, we experimentally and theoretically explore the creation and time evolution of vortex lines in the polar magnetic phase of a trapped spin-1 Rb-87 Bose-Einstein condensate. A process of phase-imprinting a nonsingular vortex, its decay into a pair of singular spinor vortices, and a rapid exchange of magnetic phases creates a pair of three-dimensional, singular singly-quantized vortex lines with core regions that are filled with atoms in the ferromagnetic phase. Atomic interactions guide the subsequent vortex dynamics, leading to core structures that suggest the decay of the singly-quantized vortices into half-quantum vortices. Superfluid vortices are important in many diverse systems, including spinor Bose-Einstein condensates. Here, the experimental and theoretical analysis of the creation and time evolution of vortices in the polar phase of a spin-1 Bose-Einstein condensate is presented, showing the evolution of single-quantum vortices towards half-quantum ones.