Quantum Hall Effect
A quantum mechanical version of the Hall effect observed in 2D electron gases at low temperatures and intense magnetic fields, where Hall resistance is quantized in integer multiples of h/e².
Governing formula
R_H = h / (ν e²), ν = 1, 2, 3...
SI unit
Ω (Von Klitzing Constant R_K ≈ 25812.807 Ω)
In depth
Discovered by Klaus von Klitzing in 1980. High magnetic fields quantize electron motion into discrete Landau energy levels. The exact quantization of Hall resistance is independent of sample impurities, serving as the international resistance standard.
Examples in the real world
Defining the international SI Ohm resistance standard using GaAs heterostructure quantum Hall devices.