1. Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak
Ridge, Tennessee 37831, United States
2. University of California at Berkeley, 210 Hearst Memorial Mining Building, Berkeley, California 94720, United States
3. Tsinghua University, and Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
4. RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan