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 toward 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.
Highlights
We experimentally study the dynamics of quantum knots in a uniform magnetic field in spin-1 BoseEinstein condensates
The knot is created in the polar magnetic phase, which rapidly undergoes a transition toward the ferromagnetic phase in the presence of the knot
Spinor Bose-Einstein condensates (BECs) are one of the most fascinating systems available for the study of topological defects due to the diverse range of broken symmetries associated with the different magnetic phases of the system
Summary
We experimentally study the dynamics of quantum knots in a uniform magnetic field in spin-1 BoseEinstein condensates. On the order of seconds, the knot is completely destroyed and we observe a spatial rearrangement of magnetic phases, such that the polar phase occupies the central region of the condensate, surrounded by a mixed-phase region that approaches the ferromagnetic phase at the condensate boundary. Quite surprisingly, this emergent texture is that of a singular polar-core spin vortex [7,25,26]. Within this formalism, the condensed gas is described by an order parameter which in the
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