# Decay of a Quantum Knot

## TL;DR

This paper experimentally investigates the decay dynamics of quantum knots in spin-1 Bose-Einstein condensates, revealing their transformation into stable polar-core spin vortices and suggesting universal topological behavior.

## Contribution

It demonstrates the creation and decay of quantum knots in BECs, showing their evolution into stable vortices and highlighting a universal topological transition.

## Key findings

- Quantum knots decay into polar-core spin vortices.
- The polar-core spin vortex has a lifetime comparable to the condensate.
- The observed transition suggests universality in topological defect evolution.

## Abstract

We experimentally study the dynamics of quantum knots in a uniform magnetic field in spin-1 Bose-Einstein condensates. The knot is created in the polar magnetic phase, which rapidly undergoes a transition towards the ferromagnetic phase in the presence of the knot. The magnetic order becomes scrambled as the system evolves, and the knot disappears. Strikingly, over long evolution times, the knot decays into a polar-core spin vortex, which is a member of a class of singular SO(3) vortices. The polar-core spin vortex is stable with an observed lifetime comparable to that of the condensate itself. The structure is similar to that predicted to appear in the evolution of an isolated monopole defect, suggesting a possible universality in the observed topological transition.