What effect quantizes the Hall conductance into integer multiples of e²/h?

The integer quantum Hall effect quantizes Hall conductance into integer multiples of e²/h.

It appears in a two-dimensional electron system subjected to a strong magnetic field and very low temperature. The transverse Hall conductance forms exceptionally precise plateaus rather than changing smoothly. The integer filling factor identifies how many quantum levels are occupied.

Klaus von Klitzing discovered the effect in 1980 while studying silicon metal-oxide-semiconductor structures. He received the 1985 Nobel Prize in Physics for the discovery of the quantized Hall effect. Because the value is extraordinarily reproducible, the effect became important in precision measurement and helped define electrical resistance standards.

The integer effect differs from the fractional quantum Hall effect, in which the filling factor can be a fraction and strongly interacting electrons form collective states. Both phenomena require effectively two-dimensional motion, but the fractional case cannot be explained by independent electrons alone.