Researchers Create Stable Vortex Knots in Liquid Crystals

Liquid Crystals
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Scientists have generated stable, particle-like vortex knots within chiral nematic liquid crystals, materials commonly used in LCD displays. These topological structures resemble knotted loops of magnetic field lines and remain intact without external support. The knots can be reversibly transformed between different configurations using electric fields.

The structures form when researchers apply voltage pulses to fuse or split existing knots. Chiral nematic phases provide the twisted molecular arrangement necessary for knot stability in three dimensions. Previous attempts produced unstable knots that unraveled quickly.

Electric fields control the knot dynamics precisely. Short pulses trigger fusion of two simple knots into more complex forms, while adjusted pulses split them apart. The process occurs at room temperature and requires modest voltages compatible with display technology.

The knots behave as quasiparticles with conserved topological charges. They exhibit hopping motion under applied fields and interact with boundaries in the liquid crystal cell. Stability persists for hours after field removal.

This achievement confirms theoretical predictions about topological solitons in chiral fluids. Researchers used confocal microscopy to visualize the three-dimensional director field around each knot. Multiple knot types, including trefoil and hopfion variants, were observed.

The platform enables direct manipulation of topological defects. Knot creation involves nucleating disclination loops that link into desired configurations. Reconfiguration preserves overall linking numbers consistent with topology conservation laws.

Applications extend beyond fundamental physics. Controlled knot arrays could store or process information through their topological states. The system offers an accessible testbed for studying knot dynamics in other condensed matter contexts.

The work builds on decades of research into topological defects in liquid crystals. Earlier studies produced skyrmions and torons, but stable three-dimensional knots required the specific chirality and field protocols developed here.

Researchers anticipate extending the approach to other soft matter systems. Ferroelectric nematics or active liquids may support additional knot varieties. The electric control mechanism demonstrates scalability for device integration.

This development provides experimental access to knotted field configurations previously confined to theory. It opens routes to exploring topological protection mechanisms in controllable environments. Future experiments aim to create larger knot ensembles and measure their collective behavior.

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