Plasmons on Wide Epitaxially-grown Quantum Wells

Quantum wells can now be grown by molecular beam epitaxy in the Gal~xAlxAs system with almost any desired electron confinement potential V (z) in the growth or z direction. The wells can be filled by remote doping, giving finely controllable high-mobility electron gases with a dimensionality between two and three. Grating coupler techniques permit observation at finite surface wavenumber of the infrared plasmon modes of these structures. This provides in principle a window onto fundamental and applicable many-electron physics. Of special interest are the 'pseudo-jellium' properties of parabolic and parabolic~linear wells, which are discussed in detail here. A theorem applicable to more general wells is also introduced.