University of California Si/SiGe Qubits Hit 5 meV Valley Splitting

Researchers at the University of California and University at Buffalo demonstrated 5 meV valley splitting through simulations of silicon-germanium qubits, a result that surpasses values reported in nearly all previous theoretical studies. This advance addresses a critical challenge in scaling silicon-based quantum computing, where maintaining stable qubit performance has been hampered by the small and inconsistent energy gap known as valley splitting. The team employed a Si/SiGe heterostructure design, combining a narrow quantum well, a small germanium spike, and a pure-germanium cap, to enhance this crucial property. Device-scale simulations, incorporating the impact of atomic-level imperfections, demonstrated a tight distribution across disorder…