title: Optical Control of Donor Spin Qubits in Silicon.
abstract: We show how to achieve optical, spin-selective transitions from the ground state to excited orbital states of group-V donors (P, As, Sb, Bi) in silicon. We consider two approaches based on either resonant, far-infrared (IR) transitions of the neutral donor or resonant, near-IR excitonic transitions. For far-IR light, we calculate the dipole matrix elements between the valley-orbit and spin-orbit split states for all the goup-V donors using effective mass theory. We then calculate the maximum rate and amount of electron-nuclear spin-polarization achievable through optical pumping with circularly polarized light. We find this approach is most promising for Bi donors due to their large spin-orbit and valley-orbit interactions. Using near-IR light, spin-selective excitation is possible for all the donors by driving a two-photon Λ-transition from the ground state to higher orbitals with even parity. We show that externally applied electric fields or strain allow similar, spin-selective Λ-transition to odd-parity excited states. We anticipate these results will be useful for future spectroscopic investigations of donors, quantum control and state preparation of donor spin qubits, and for developing a coherent interface between donor spin qubits and single photons.
authors.affiliation: Joint Quantum Institute, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA; Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, MD 20742, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Gullans
authors.affiliation: Joint Quantum Institute, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA; Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, MD 20742, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Taylor