Although first demonstrated in GaAs / Al x Ga 1-x As quantum wells, QCSE started to generate interest after its demonstration in Ge / SiGe. Differently from III/V semiconductors, Ge/SiGe quantum well stacks can be epitaxially grown on top of a silicon substrate, provided the presence of some buffer layer in between the two. This is a decisive advantage as it allows Ge/SiGe QCSE to be integrated with CMOS technology and silicon photonics systems.