QuTech Silicon Qubits Achieve 760µeV Valley Split via Confinement

Researchers at QuTech and the University of Wisconsin-Madison have demonstrated an increase in valley splitting within silicon quantum wells, achieving 760µeV through electrostatic confinement, a critical step toward more stable qubits. The team reports measuring an average valley splitting of 0.40(6) meV and a singlet-triplet splitting of 0.24(7) meV across a linear array of four quantum dots. This work reveals a relationship between valley splitting and orbital energy, with an average linear coefficient of approximately 0.22 meV/meV, suggesting a pathway to tailor qubit performance through design. These findings demonstrate that strong confinement can enhance valley splitting, establishing a path toward scalable, shuttling-based quantum architectures in low-disorder heterostructures. A correlation…