Optical Control of Donor Spin Qubits in Silicon

Area of Science:

• Solid State Physics
• Quantum Information Science
• Materials Science

Background:

• Group-V donors in silicon are promising for spin qubits.
• Achieving spin-selective optical transitions is crucial for qubit control and readout.
• Existing methods for manipulating donor spins have limitations.

Purpose of the Study:

• To investigate optical, spin-selective transitions from ground to excited orbital states in silicon group-V donors (P, As, Sb, Bi).
• To explore two distinct optical pumping approaches: far-infrared (IR) and near-infrared (IR) transitions.
• To assess the feasibility of these methods for quantum control and coherent interfaces.

Main Methods:

• Effective mass theory was used to calculate dipole matrix elements for far-IR transitions.
• Calculations of electron-nuclear spin polarization rates under optical pumping with circularly polarized light.
• Investigation of two-photon Lambda-transitions for near-IR excitation, including the effects of electric fields and strain.

Main Results:

• Far-IR optical pumping shows potential for spin polarization, particularly for Bismuth (Bi) donors due to strong spin-orbit and valley-orbit interactions.
• Near-IR two-photon Lambda-transitions enable spin-selective excitation to even-parity orbitals for all group-V donors.
• Electric fields or strain can induce spin-selective Lambda-transitions to odd-parity orbitals.

Conclusions:

• Optical methods provide viable pathways for spin-selective control of group-V donor states in silicon.
• These findings support future spectroscopic studies and the development of donor spin qubits.
• The proposed techniques are key for creating coherent interfaces between donor spin qubits and photons.