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[2] Fudan Univ, Inst Nanoelect Devices & Quantum Comp, Shanghai 200433, Peoples R China
[3] Fundan Univ, Zhangjiang Fudan Int Innovat Ctr, Shanghai 201210, Peoples R China
[4] Fudan Univ, State Key Lab Surface Phys, Shanghai 200433, Peoples R China
[5] Fudan Univ, Dept Phys, Shanghai 200433, Peoples R China