Spin-Valley Coupling Anisotropy and Noise in CMOS Quantum Dots

One of the main advantages of silicon spin qubits over other solid-state qubits is their inherent scalability and compatibility with the 300-mm complementary metal oxide semiconductor (CMOS) fabrication technology that is already widely used in the semiconductor industry, while maintaining high readout and gate fidelities. We demonstrate the detection of a single electron spin using energy-selective readout in a CMOS-fabricated nanowire device with an integrated charge detector. We measure a valley splitting of 0.3 meV and 0.16 meV in two similar devices. The anisotropy of the spin-valley mixing is measured and shown to follow the dependence expected from the symmetry of the local confinement, indicating low disorder in the region of the quantum dot. Finally the charge noise in the strong spin-valley coupling regime is investigated and found to induce fluctuations in the qubit energy in the range of 0.6 GHz/ root Hz.