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Quantum Hall effect
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Hall resistance quantised in 2D electron gases.
In a 2D electron gas at low temperature and high field the Hall resistance is quantised: R_H = h/(νe²), with plateaus independent of material details. Used as a resistance standard.
25,812.807 Ω for ν = 1.
Fractional versions reveal exotic quasi-particles.
In more detail
The quantum Hall effect occurs in two-dimensional electron systems at low temperatures and strong magnetic fields. The Hall conductance is quantised in integer or fractional multiples of e squared over h.
Real-world uses
- The quantum Hall effect defines the standard of electrical resistance.
- Condensed matter research uses it to study topological phases.
- Metrologists use the quantum Hall effect to define the ohm with very high precision.
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Frequently asked questions
What is quantised?
The Hall resistance, which takes precise values independent of material details.
Who discovered it?
Klaus von Klitzing in 1980, who received the Nobel Prize.
Why is the quantum Hall resistance so precise?
It depends only on fundamental constants, so it does not vary with material details.
Related topics in Quantum Mechanics
Feynman path integral · Quantum electrodynamics · Casimir effect · Superfluidity · Superconductivity and BCS theory