Mesoscopic phenomena in semiconductor nanostructures by quantum design

The energy levels, wave functions, optical matrix elements, and scattering rates of electrons can be tailored at will using semiconductor nanostructures as building blocks for practically any kind of potential. This allows the design and experimental realization of new artificial materials and devices, with interesting optical and transport properties arising from quantum confinement, tunneling, and quan- tum coherence on a mesoscopic scale ranging typically from 1 to 100 nm. This approach is illustrated with a number of recent examples based on experiments and calculations, such as resonant tunneling through double barriers, quantum interference phenomena in transport and optical absorption, bound states in the continuum, quantum well ‘‘pseudomolecules’’ with giant nonlinear optical susceptibilities, and quantum cascade lasers.