The knot theory originates in Lord Kevin's model proposed in 1867 that atoms are made of vortex rings or knots. Although the hypothesis was proved incorrect, the knot theory has since then proliferated in both mathematics and physics. One peculiar category of knots—the torus knots—are disjointed and linked closed loops, nesting to construct complete ring tori. Physicists find the torus knot a suitable candidate for building hopfions—three-dimensional (3D) topological states that resemble particle-like objects.