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Spatial and energy resolution of electronic states by shot noise
Shot-noise measurements are widely used for the characterization of nonequilibrium configurations in
electronic conductors. The recently introduced quantum tomography approach was implemented for the studies
of electronic wave functions of few-electron excitations created by periodic voltage pulses in phase-coherent
ballistic conductors based on the high-quality GaAs two-dimensional electron gas. Still relying on the manifestation
of Fermi correlations in noise, we focus on the simpler and more general approach beneficial for local
measurements of energy distribution (ED) in electronic systems with arbitrary excitations with well-defined
energies and random phases. Using biased diffusive metallic wire as a test bed, we demonstrate the power of this
approach and extract the well-known double-step ED from the shot noise of a weakly coupled tunnel junction.
Our experiment paves the way for local measurements of generic nonequilibrium configurations applicable to
virtually any conductor.