Single-Electron-Spin Measurements in Si-Based Semiconductor Nanostructures

In this chapter, we review the experimental efforts that focus on the measurement of single-electron spins in two particular Si-based semiconductor nanostructure systems. First, we describe experiments in a real transistor structure (i.e., a submicrometer commercial Si field effect transistor) in which the source/drain channel is used to electrically detect the spin states of an adjacent single paramagnetic spin center. This transistor structure is similar to a number of proposed spin-based qubit architectures that can be used as a potential quantum information processor. Second, we describe the effort to fabricate similar devices in specially designed semiconductor structures that promise greater control over electron spin, the ability to entangle two spins, and to eventually build a scalable quantum processor. In these engineered structures, quantum dots are created by metallic gates patterned over a 2D electron gas in a strained silicon-germanium heterostructure. In addition to the discussion of fabrication issues, we also show examples of single-electron-spin measurements in the few-electron regime of quantum dots.