Electrical detection of coherent 31P spin quantum states

In recent years, a variety of solid-state qubits has been realized, including quantum dots [1, 2], superconducting tunnel junctions [3, 4] and point defects [5, 6]. Due to its potential compatibility with existing microelectronics, the proposal by Kane [7, 8] based on phosphorus donors in Si has also been pursued intensively [9, 10, 11]. A key issue of this concept is the readout of the 31P quantum state. While electrical measurements of magnetic resonance have been performed on single spins [12, 13], the statistical nature of these experiments based on random telegraph noise measurements has impeded the readout of single spin states. In this letter, we demonstrate the measurement of the spin state of 31P donor electrons in silicon and the observation of Rabi flops by purely electric means, accomplished by coherent manipulation of spin-dependent charge carrier recombination between the 31P donor and paramagnetic localized states at the Si/SiO2 interface via pulsed electrically detected magnetic resonance. The electron spin information is shown to be coupled through the hyperfine interaction with the 31P nucleus, which demonstrates the feasibility of a recombination- based readout of nuclear spins.