Abstract
Quantum computers have been the dream of many scientists for over thirty years but the fact such devices still consist of only a handful of quantum bits (qubits) highlights the fact that this is not a trivial concept. However the potential of powerful parallelisation, which could out perform classical computers remains a huge incentive for researchers. Interest in donors in silicon has grown since being put forward as a possible candidate for a qubit in 1998 by Kane. Group V atoms, such as phosphorus, substitute into the silicon lattice but possess an extra outer shell electron compared to the neighbouring silicon atoms. This electron orbits the donor much like a hydrogen atom trapped in a silicon crystal. Despite overlapping with thousands of silicon atom, the donor electron experiences very little interaction with its surroundings leading to long spin lifetimes and coherence times. In this thesis the orbital state of donor electrons is explored. Electrical detection is used as a method of reading out coherent and incoherent manipulations of donor orbits. This is due to the high sensitivity achievable with electrical measurements. This work looked the detection mechanism in low and high intensity regimes as well as exploring the dynamics of the electron donor system in the time domain. Such experiments are use to measure the saturation of absorption and the electron-ion recombination rate (a quantity for which a range of values have previously been reported). Finally, the first electrical detection of coherent control of orbital states in silicon donors is presented, with T2* found to be 30 — 50ps.