An optical and/or electronic device is operated by degeneracy of density of states caused by confinement of electrons in a fractal region having a self-similarity. An AlGaAs/GaAs light emitting device is configured by distributing GaAs quantum dots in a fractal arrangement and confining them in i-type AlGaAs. A single-electron state of the quantum dot array exhibits degeneracy of density of states. Further, a strong quantum chaos is generated to bring about degeneracy of density of states by applying a random magnetic field by addition of a magnetic impurity to the region having a self-similarity.