  This review describes recent groundbreaking results in Si, Si/SiGe and
dopant-based quantum dots, and it highlights the remarkable advances in
Si-based quantum physics that have occurred in the past few years. This
progress has been possible thanks to materials development for both Si quantum
devices, and thanks to the physical understanding of quantum effects in
silicon. Recent critical steps include the isolation of single electrons, the
observation of spin blockade and single-shot read-out of individual electron
spins in both dopants and gated quantum dots in Si. Each of these results has
come with physics that was not anticipated from previous work in other material
systems. These advances underline the significant progress towards the
realization of spin quantum bits in a material with a long spin coherence time,
crucial for quantum computation and spintronics.
