Here we report on long-lived hidden topological states in thermally quenched, chiral nematic droplets, formed from string-like, triangular and polyhedral constellations of monovalent and polyvalent singular point defects. These topological defects are regularly packed into a spherical liquid volume and stabilized by the elastic energy barrier due to the helical structure and confinement of the liquid crystal in the micro-sphere. We observe, for the first time, topological three-dimensional point defects of the quantized hedgehog charge q=-2,-3. These higher-charge defects act as ideal polyvalent artificial atoms, binding the defects into polyhedral constellations representing topological molecules.
COBISS.SI-ID: 30270503
We demonstrate full control over the creation, manipulation and analysis of topological charges that are pinned to a microfibre in a nematic liquid crystal. Oppositely charged pairs are created through the Kibble–Zurek mechanism by applying a laser-induced local temperature quench in the presence of symmetry-breaking boundaries. The pairs are long-lived, oppositely charged rings or points that either attract and annihilate, or form a long-lived, charge-neutral loop made of two segments with a fractional topological charge.
COBISS.SI-ID: 2786916
In this paper, we show that surfaces of diverse biofibers, including spider silks and cellulosic fibers, can be easily sensed by depositing droplets of a nematic fluid onto the fibers. The droplets reveal the surface properties of the fibers via their optical images, notably showing also the fiber chirality. Further, the droplets are used to study the entanglement of biofibers, as a route toward novel biological and bioinspired materials.
COBISS.SI-ID: 2917220
Droplets of chiral liquid crystals, or cholesterics, typically exhibit an intriguing radial defect which results from frustrations in the molecular order. This configuration shows a fascinating analogy to the Dirac monopole, a hypothetical magnetic charge, and plays a crucial role in the droplet optical properties, recently exploited to produce microlasers. Despite its evident interest, the nature of this disclination remains uncertain. We experimentally show, by studying spherical cholesteric shells, that it is composed of two line defects that wrap around each other on a double-helix str ucture. By tuning the system chirality, we can make this configuration dissociate into two independent stacks of disclination rings. The transition between configurations is reversible and entails an unexpected defect waltz dynamics.
COBISS.SI-ID: 3043172
In this article, we show how several abstract concepts manifest elegantly as observable and measurable features in nematic colloids with knotted disclination lines. Construction of medial graphs, surfaces, and Jones polynomials is showcased directly on experimental images, and adapted for the specific system of colloidal crystals in a twisted nematic cell. We discuss the correspondence between topological concepts and experimental observation, which is essential for building the bridge between mathematical and physical communities.
COBISS.SI-ID: 2787940