Vorticity in a Superfluid.

William Frank Vinen

Yosuke Minowa, Yuki Yasui, Shota Aoyagi +1 more

We demonstrated the visualization of quantized vortices in superfluid helium with silicon nanoparticles. Nanoparticles were produced in situ with pulsed laser ablation and dispersed within the superfluid helium. The dispersed nanoparticles were utilized to decorate the quantized vortices, allowing for the imaging and visualization of the dynamics of the vortices, such as vortex reconnection.

Lucy J. Campbell

Sang Won Seo, Woo Jin Kwon, Seji Kang +1 more

Quantum vortices with half the quantum circulation, known as half-quantum vortices (HQVs), have been observed in various spinor superfluid systems recently. Because of their nonsingular cores, the interaction of HQVs is expected to be different from that of vortices in a conventional scalar superfluid, which can lead to a new class of superfluid dynamics. Here, we report on a collision experiment of two HQV pairs in an antiferromagnetic spinor Bose-Einstein condensate. The observed scattering motions of the HQVs reveal the short range interactions that arise from their ferromagnetic cores. Additionally, we investigate the relaxation dynamics of turbulent superflow containing many HQVs to find that spin wave excitations are generated and maintained by the collisional motions of the HQVs during dissipative evolution. These results provide new insight into the vortex dynamics in spinor superfluids.

Jelena Stajic

Superfluidity When stirred, superfluids react by creating quantized vortices. Studying the dynamics of these vortices, especially in the strongly interacting regime, is technically challenging. Sachkou et al. developed a technique for the nondestructive tracking of vortices in thin films of superfluid helium-4. Their system contained a microtoroid optical cavity coated by a thin film of helium-4, in which vortices were created by using laser light. When imaging the subsequent dynamics of the vortices, the researchers found that coherent dynamics strongly dominated over dissipation. Science , this issue p. [1480][1] [1]: /lookup/doi/10.1126/science.aaw9229

Katepalli R. Sreenivasan