In a typical QHE experiment, a MOSFET is subjected to a large magnetic field of order 15 T, at a temperature of order 1 K. There is a twodimensional electron gas maintained in the inversion layer of the MOSFET, the plane of which is aligned perpendicular to the magnetic field. When an electric field is applied in the plane, the corresponding Hall resistance is found to be quantized in units of
where h is Planck's constant, e the elementary charge, and n an integer. This is referred to as the Integer Quantum Hall Effect (IQHE).
In 1982, Daniel Tsui and Horst Stormer discovered the Fractional Quantum Hall Effect. Working at lower temperatures and stronger magnetic fields, they found a Hall resistance quantized in units of 3h / e^{2}, i.e. n = 1/3. Other fractional quantizations  for example, 2/5, 3/5, and 2/7  were subsequently found. The FQHE was explained in 1983 by Robert Laughlin, using a manybody wavefunction that has a lower energy than the singleparticle energy.
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