Experimental probing of quantum-well eigenstates

We measured the spatial variation of the probability densities in the first few electron states of a GaAs/${\mathrm{Al}}_{\mathrm{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathrm{x}}$As quantum well. This result was obtained from the optical determination of the energies of the bound states as a function of the position of a highly localized perturbation, consisting of one isoelectronic substituted cation plane containing either indium (attractive potential) or aluminum (repulsive potential). A series of samples was prepared, each with the probe plane in a different position, scanning thus the whole width of the quantum wells.