News Item

"Snell's Law for a vortex dipole in a Bose-Einstein condensate" by Michael M. Cawte, Xiaoquan Yu, Brian P. Anderson, Ashton S. Bradley has received the Select label. Warm congratulations to the authors!

This paper provides a useful guide for the behaviour of vortex dipoles as they pass through interfaces of sharply changing density, including a thorough numerical study and consequent analysis. As part of this analysis, the authors compare the values of the reflection/refraction vs. incident angles in vortex dipoles with a Snell’s law-like analytical prediction, achieving good agreement between the two before and after the interface. However, the authors found that when passing near the interface the dipole can exhibit dynamics that depart significantly from standard ray optics, involving transient capture by the interface. They conclude that despite the added complexity, an analogue Snell’s law is still applicable for the incoming and outgoing dipole paths when interacting with a sharp interface. This interesting and thorough study could guide future experiments on vortices in flattened geometries.