Non-Abrikosov Vortex and Topological Knot in Two-gap Superconductor

We establish the existence of topologically stable knot in two-gap superconductor whose topology $\pi_3(S^2)$ is fixed by the Chern-Simon index of the electromagnetic potential. We present a helical magnetic vortex solution in Ginzburg-Landau theory of two-gap superconductor which has a non-vanishing condensate at the core, and identify the knot as a twisted magnetic vortex ring made of the helical vortex. We discuss how the knot can be constructed in the recent two-gap $\rm MgB_2$ superconductor.Comment: 4 pages, 3 figure

Monopoles and Knots in Skyrme Theory

We show that the Skyrme theory actually is a theory of monopoles which allows a new type of solitons, the topological knots made of monopole-anti-monopole pair,which is different from the well-known skyrmions. Furthermore, we derive a generalized Skyrme action from the Yang-Mills action of QCD, which we propose to be an effective action of QCD in the infra-red limit. We discuss the physical implications of our results.Comment: 4 pages. Phys. Rev. Lett. in pres

Knots in Condensed Matters

We propose two types of topologically stable knot solitons in condensed matters, one in two-component Bose-Einstein condensates and one in two-gap superconductors. We identify the knot in Bose-Einstein condensates as a twisted vorticity flux ring and the knot in two-gap superconductors as a twisted magnetic flux ring. In both cases we show that there is a remarkable interplay between topology and dynamics which transforms the topologcal stability to the dynamical stability, and vise versa. We discuss how these knots can be constructed in the spin-1/2 condensate of $^{87}{\rm Rb}$ atoms and in two-gap superconductor of $MgB_2$.Comment: 9 pages, 4 figure