We apply the full power of modern electronic band structure engineering and epitaxial hetero-structures to design a transistor that can sense and control a single donor electron spin. Spin resonance transistors may form the technological basis for quantum information processing. One and two qubit operations are performed by applying a gate bias. The bias electric field pulls the electron wave function away from the dopant ion into layers of different alloy composition. Owing to the variation of the g-factor (Si:g=1.998, Ge:g=1.563), this displacement changes the spin Zeeman energy, allowing single-qubit operations. By displacing the electron even further, the overlap with neighboring qubits is affected, which allows two-qubit operations. Certain Silicon-Germanium alloys allow a qubit spacing as large as 200 nm, which is well within the capabilities of current lithographic techniques. We discuss manufacturing limitations and issues regarding scaling up to a large size computer.

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We study a scheme for electrical detection of the spin resonance of a single-electron trapped near a field effect transistor (FET) conduction channel. In this scheme, the resonant Rabi oscillations of the trapped electron spin cause a modification of the average charge of a shallow trap, which can be detected through the change in the FET channel resistivity. We show that the dependence of the channel resistivity on the frequency of the rf field can have either peak or dip at the Larmor frequency of the electron spin in the trap.There has been a lot of interest recently in a few and single electron spin detection and measurement. The motivation comes primarily from quantum computing, where ability to manipulate and to measure single spin is the basis for several architecture proposals [1][2][3]. There is also significant interest in the study of local electronic environment, e.g., by means of local electron spin resonance. Such information would be valuable both for the conventional semiconductor industry, which has to deal with continuously decreasing feature sizes, as well as such novel research directions as spintronics where the utilization of electronic spin degrees of freedom may lead to conceptually new devices [4].The main difficulty of a few spin detection and measurement lies in the inherent weakness of magnetic interaction, making direct measurement of a small number of spins challenging. Current state-of-the-art direct detection techniques, e.g., magnetic resonance force microscopy [5], have only recently achieved the sensitivity of about 100 fully polarized electron spins [6]. Unlike single spin effects, single-electron charge signals are much easier to measure. For instance, it is well established that the events of capture and release of electron by a single trap near conducting channel in a field effect transistor (FET) can be measured as a random telegraph signal (RTS) in the channel resistivity [7,8]. Here we study a setup in which single-electron spin resonance can be detected through its influence on RTS. The effect appears both as the change of the time-average resistivity as well as in the ratio of filled to empty trap lifetimes. This setup is motivated by the recent experiments of Xiao and Jiang [9], where they analyze changes in the statistics of RTS jumps as a manifestation of the electron spin resonance. A related scheme for electrical spin resonance (ESR) detection by measuring current through a semiconductor quantum dot was recently proposed by Engel and Loss [10].There is a variety of traps that can occur in real systems. Here we consider two representative cases schematically shown in Figs. 1 and 2. They correspond to the spinless and spinful ''empty'' states of the electron trap near the FET channel. The conduction channel chemical potential can be varied with a gate. The single-electron levels in the trap are split by the external magnetic field B 0 , ÿ1=2 ÿ 1=2 g B B 0 , where g is the electron g factor in the trap and B is the Bohr magneton. There is an oscillating magnetic field...

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