Before their new discovery, physicists thought that except quarks and other particles, the charge of elementary particles in the universe was an integer multiple of the charge of an electron-e (e =1.6×10-19 coulomb). Quarks can have a charge of 1e/3 or 2e/3 depending on the type. Quarks can only exist in the nucleus, unlike electrons that can flow freely. Therefore, physicists do not expect to see particles or excited States with fractional electron charges like quarks in ordinary condensed systems.

This idea was challenged in 1982, when Cui Qi and Strom discovered the fractional Hall effect in two-dimensional electronic systems. A year later, Labrin put forward a novel theory that a two-dimensional electron system can form an incompressible quantum fluid with fractional charge due to Coulomb interaction between electrons under a strong magnetic field. The appearance of fractional charge can be said to be very mysterious and unexpected, but it can actually be deduced from known quantum rules.

Labrin also tried to use his theory to explain why quarks have fractional electron charges, although this idea has not been successful so far. After laughlin's theory appeared, it was immediately judged as a correct idea by theoretical experts. But for many people, his theory is still difficult to understand. In the following five or six years, many important papers appeared one after another, which explained the obscure concepts in Labrin's theory more clearly, and further extended his theory to many different physical conditions, making the whole theory more complete. Let's briefly explain what the fractional quantum Hall effect is and its theoretical explanation.