Optical Probes in the Quantum Hall Regime

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Abstract
Semiconductor nanostructures in which mobile electrons reside in a specific spatial region, such as a thin quantum well formed by heterojunction layers on the order of 100 Å in thickness, constitute a particularly striking physical system. The mobile electrons in such a system form a “two-dimensional electron gas.” In a uniform semiconductor electrons scatter off the ionized donor dopants, but in a two-dimensional electron gas the electrons can be separate from the dopants and enjoy extraordinarily long mean free paths (many micrometers) at cryogenic temperatures. In the past dozen years or so, this unique property has provided an enormously rich field for the study of electron transport phenomena, ranging from ballistic motion in small device structures to many-electron correlations in strong magnetic fields