Atomic fluctuations lifting the energy degeneracy in Si/SiGe quantum dots

• DOI: 10.48550/arxiv.2112.09606
• Publication Date: 2021-01-01
• Authors: Brian Paquelet Wuetz; Merritt P. Losert; Sebastian Koelling; Lucas E. A. Steho...; Anne-Marije J. Zw...; Stephan G. J. Phi...; Mateusz Mądzik; Xiao Xue; Guoji Zheng; Mario Lodari; Sergey V. Amitonov; Nodar Samkharadze; Amir Sammak; L. M. K. Vandersypen; Rajib Rahman; S. N. Coppersmith; Oussama Moutanabbir; Mark Friesen; Giordano Scappucci
• Keywords: Degeneracy (biology); Energy level splitting; Atomic units

Electron spins in Si/SiGe quantum wells suffer from nearly degenerate conduction band valleys, which compete with the spin degree of freedom formation qubits. Despite attempts to enhance valley energy splitting deterministically, by engineering a sharp interface, fluctuations remain serious problem for qubit uniformity, needed scale up large processors. Here, we elucidate and statistically predict holistic integration 3D atomic-level properties, theory transport. We find that concentration Si Ge atoms within landscape interfaces can explain observed spread measurements on many dot devices. Against prevailing belief, propose boost these random alloy composition incorporating well splitting.