SiGe/Si(111)/SiGe heterostructure for Si spin qubits with electrons confined in L valley of conduction band

Quantum Physics [Submitted on 15 Apr 2026] SiGe/Si(111)/SiGe heterostructure for Si spin qubits with electrons confined in L valley of conduction band Takafumi Tokunaga, Hiromichi Nakazato In Si(111) crystals, a strong biaxial tensile strain applied within the (111) plane is considered to shift the lowest energy point of the conduction band from the \Delta valley to the L valley. Electrons confined in this L valley experience a splitting of their quadruply degenerate energy levels into an undegenerate single-level ground state (L1) and a triply degenerate excited state (L3). The energy of the single-level ground state is sufficiently low relative to the energies of the L3 valley and the \Delta valley, making it optimal as a two-level system for a qubit. Using deformation potential theory and incorporating quantum effects from electron confinement in the SiGe/Si(111)/SiGe structure, we determine the value of the biaxial tensile strain causing the shift of the conduction band energy minimum from the \Delta valley to the L valley, along with the corresponding Ge concentration. We also calculate the critical thickness for the plastic relaxation of the Si quantum well under this large biaxial tensile strain and examine the feasibility of realizing it as a SiGe/Si(111)/SiGe heterostructure. Comments: 11 pages, 10 figures Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2604.13435 [quant-ph]   (or arXiv:2604.13435v1 [quant-ph] for this version)   https://doi.org/10.48550/arXiv.2604.13435 Focus to learn more Submission history From: Takafumi Tokunaga [view email] [v1] Wed, 15 Apr 2026 03:27:52 UTC (513 KB) Access Paper: HTML (experimental) view license Current browse context: quant-ph < prev   |   next > new | recent | 2026-04 References & Citations INSPIRE HEP NASA ADS Google Scholar Semantic Scholar Export BibTeX Citation Bookmark Bibliographic Tools Bibliographic and Citation Tools Bibliographic Explorer Toggle Bibliographic Explorer (What is the Explorer?) Connected Papers Toggle Connected Papers (What is Connected Papers?) Litmaps Toggle Litmaps (What is Litmaps?) scite.ai Toggle scite Smart Citations (What are Smart Citations?) Code, Data, Media Demos Related Papers About arXivLabs Which authors of this paper are endorsers? | Disable MathJax (What is MathJax?)