Spin qubits

Silicon-based spin qubits are of significant interest for applications to quantum information processing due to their small size and potential for scalability. However, implementations to date have been hindered by the presence of valley degeneracy, which causes spin decoherence, and by silicon’s weak spin-orbit coupling, which necessitates the use of complicated micromagnet fabrication to create an artificial magnetic field gradient. Our study presents measurements of the valley spectrum in a double-quantum dot device and establishes two-axis control of a singlet-triplet qubit using an artificial magnetic field gradient generated by the valley subspace. These findings have important ramifications for scaling up silicon-based spin qubits. Then we are working towards a two qubit device so that we can further develop both single and two qubit tomographic techniques in SiGe.