- Speaker: Prof. Hosung Seo (Ajou University)
- Date: Wednesday, January 12, 2018, at 17:00
- Place: Jungho Seminar
In recent years, remarkable advances have been reported in the development of defect spin
quantum bits (qubits) in semiconductors for solid-state quantum information science and
technology. Promising spin qubits include the nitrogen-vacancy center in diamond, dopants in
silicon, and the silicon vacancy and divacancy spins in silicon carbide. In this talk, I will
highlight some of our recent efforts devoted to defect spin qubits in wide-gap semiconductors [1-
4]. In the first part of the talk, I will explain basic concepts of using point defects in
semiconductors as qubits and their applications. Then, I will describe our recent combined
theoretical and experimental study on remarkably robust quantum coherence found in the
divancancy qubits in silicon carbide [2]. We used a quantum bath model combined with a cluster
expansion method to identify the microscopic mechanisms behind the unusually long coherence
times of the divacancy spins in SiC. I will also discuss progress and challenges in computational
design of new spin defects for use as qubits in piezoelectric crystals such as AlN and SiC,
including a new defect design concept using large metal ion - vacancy complexes [1]. Our first
principles calculations include DFT computations using recently developed self-consistent
hybrid density functional theory and large-scale many-body GW theory.
[1] H. Seo, H. Ma, M. Govoni, and G. Galli, Physical Review Materials 1, 075002 (2017).
[2] H. Seo, A. L. Falk, P. V. Klimov, K. C. Miao, G. Galli, and D. D. Awschalom, Nature Communications 7, 12935 (2016).
[3] H. Seo, M. Govoni, and G. Galli, Scientific Reports 6, 20803 (2016).
[4] W. F. Koehl, H. Seo, G. Galli and D. D. Awschalom, MRS Bulletin 40, 1146 (2015).