[1] Penn State Univ, Dept Phys, 104 Davey Lab, University Pk, PA 16802 USA
[2] Princeton Univ, Dept Phys, Princeton, NJ 08544 USA
[3] Peking Univ, Int Ctr Quantum Mat, Beijing 100871, Peoples R China
[4] Beijing Acad Quantum Informat Sci, Beijing 100193, Peoples R China
[5] Univ Chinese Acad Sci, CAS Ctr Excellence Topol Quantum Computat, Beijing 100190, Peoples R China