How Electrons, Repelling Each Other, Tie Knots in an Atomic Chain ✛ ✎

Original: "Topological phases of the interacting Su-Schrieffer-Heeger model: An analytical study"
arXiv:2408.01421 · 2024-08-02 · arXiv non-exclusive · independent analysis · 1 min
In a tight atomic chain, electron jostling gives birth to unbreakable knots that change the collective charge.

A chain of carbon atoms resembles a rope with weights. Where the tension is slack, waves get stuck: this is how materials where current flows only at the edges are built. But when electrons start repelling each other, knots spontaneously form in this rope. These knots are not just a disturbance. They alter the collective charge of the whole chain. Repulsion adds two corrections to the charge of each particle: the first is the familiar 'coat' of neighboring electrons, the second is a knot that can't be untied. This knot travels along the chain without changing shape, like a sailor's knot on a wet rope — only it tightens itself.

The most surprising thing: this knot carries a charge equal to half the electron's charge, even though a free electron is indivisible.

Such effects already appear in thin conducting tracks on crystals. Understanding how repulsion generates fractional charge will bring us closer to creating electronics immune to noise — where signals run along unbreakable knots.

In everyday life, the electron charge is an indivisible constant. But inside matter, where electrons are crowded, their effective charge can change, like a coin passed from hand to hand losing or gaining a 'commission'. And in the described knots, this commission goes so far that the charge splits in half.

P = \frac{1}{2} \operatorname{sgn}(m) \cdot \left( \frac{1}{1-g/\pi} + 1 - g/\pi \right) / 2
The polarization in the continuum theory equals half the sign of the mass, multiplied by a factor that depends on the interaction constant g. At g=0 the factor is 1, and we recover the classical result 1/2.
Scientists
Michael FaradayHendrik LorentzKlaus von KlitzingLev LandauFelix BlochFred Hoyle
Concepts
topological insulator Saha equation topological surface states Hill equation insulating state interaction model chern number smoothed particle hydrodynamics syk model polarity