Physics & Astronomy David Hall ’91, Amherst College: “Tying Knots in a Quantum Fluid”

Knots are familiar entities that appear at a captivating nexus of art, technology, mathematics and science. They have recently attracted significant experimental interest in contexts ranging from knotted DNA and nanostructures to nontrivial vortex knots in classical fluids. In this talk, I will discuss the first controlled
experimental creation and detection of knot solitons, which are particle-like topological excitations possessing a knotted field character. The superfluid medium within which they exist is a Bose-Einstein condensate with a temperature some tens of billionths of a degree above absolute zero. In addition to enabling future experimental studies of their properties and dynamics, these knot solitons provide a striking demonstration of the celebrated Hopf fibration, which mathematically tie together many seemingly unrelated physical phenomena.