Coulomb Blockade as a Noninvasive Probe of Local Density of States

We show that a system of two closely separated two-dimensional electron gases in a GaAs/AlGaAs system in which one is formed into a quantum dot can be used as a Coulomb blockade electrometer. The blockade is used to explore the density of states of the other electron gas which is patterned as a wire. Electron localization is observed and shows behavior in a magnetic field arising from the destruction of quantum interference and subsequent wave-function shrinkage. The dimensionality of the transport changes as the carrier concentration is increased, with the inferred density of states changing from quasi-one-dimensional to two dimensional.