Knotty problem

Kedia and colleagues believe that these knots could be made in the lab using tightly focused Laguerre–Gaussian beams. These beams have been created and studied extensively because – unlike most other beams of light – they carry orbital angular momentum.
If these optical knots can be made in the lab, they could have a number of scientific applications. Physicists are already exploring how focussed Laguerre–Gaussian beams can be used to trap ultracold atoms and this latest theoretical development could lead to new ways of trapping them. Firing such knots into a plasma or quantum fluid could also result in knot-like entities propagating through those materials, thereby offering new ways of studying these states of matter.
Once the preserve of mathematicians, knot theory is playing an increasingly important role in how physicists describe the behaviour of physical systems, ranging from liquid crystals to superconductors. Most of these descriptions arise from numerical simulations of complex systems, rather than the exact solution of the equations describing the system of interest.
The research is described in Physical Review Letters.