Interface-mediated intervalley coupling in Si

ORAL

Abstract

The conduction band degeneracy in Si is detrimental to spin qubits, for which a nondegenerate ground orbital state is desirable. The Si valley degeneracy is reduced to 2 near an interface with an insulator, and it may be lifted by the spatially abrupt change in the crystal potential. Basic physical mechanisms for Si/barrier mediated valley coupling in different situations are addressed here. Theoretical studies of the interface-induced valley splitting in Si are presented. Abrupt and smooth interface profiles are considered, and the full plane wave expansions of the Bloch functions at the conduction band minima are included. Simple criteria are suggested for optimal fabrication parameters affecting the valley splitting, emphasizing the relevance of different interface-related properties. Refs: A.L.Saraiva et al, PRB 80, 081305 R (2009); arXiv:1006.3338

*Support: BK and ALS thank CNPq, FUJB, INCT on Quantum Information, and FAPERJ. M.J.C. acknowledges Ministerio de Ciencia e Innovaci\'on (Spain). XH amd SDS thank NSA and L PS. S.D.S. also thanks CMTC.

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Authors

  • Belita Koiller

    • Instit. de Fisica, UFRJ, Rio de Janeiro, Brazil
    • U. F. Rio de Janeiro

  • Andre Saraiva

    • Instit. de Fisica, UFRJ, Rio de Janeiro, Brazil
    • U. F. Rio de Janeiro

  • M.J. Calderon

    • Instit. de Ciencia de Materiales de Madrid (CSIC), Spain

  • Xuedong Hu

    • SUNY Buffalo
    • University at Buffalo, SUNY
    • SUNY at Buffalo, NY
    • Department of Physics, University at Buffalo, SUNY, Buffalo, NY 14260-1500, USA
    • Dep. of Physics, University at Buffalo-SUNY

  • Sankar Das Sarma

    • Condensed Matter Theory Center, Department of Physics, University of Maryland, College Park, MD 20742
    • Condensed Matter Theory Center, Department of Physics, University of Maryland
    • Univ of Maryland-College Park
    • Condensed Matter Theory Center, Dept. of Physics, University of Maryland, College Park, MD
    • CMTC, Dept of Physics, University of Maryland, College Park
    • Condensed Matter Theory Center, Department of Physics, University of Maryland, College Park, Maryland 20742-4111, USA
    • Condensed Matter Theory Center, University of Maryland, College Park
    • Dep. of Physics, Condensed Matter Theory Center, University of Maryland, College Park, Maryland
    • University of Maryland
    • JQI and CMTC, University of Maryland
    • Joint Quantum Institute and Condensed Matter Theory Center, University of Maryland