Extended Data Figure 3

The focused ion beam implantation work was performed at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. DOE’s National Nuclear Security Administration under contract DE-NA-0003525. The views expressed in the article do not necessarily represent the views of the U.S. DOE or the United States Government. This work made use of the Shared Experimental Facilities supported in part by the MRSEC Program of the National Science Foundation (NSF) under award number DMR - 1419807. We thank Daniel Perry for providing the focused ion beam implantation at Sandia National Laboratories, and Di Zhu and Cheng Peng for assistance with wire bonding. N.H.W. acknowledges support from the Army Research Laboratory (ARL) Center for Distributed Quantum Information (CDQI). T.-J. L. acknowledges support from the Department of Defense (DOD) National Defense Science and Engineering Graduate Fellowship (NDSEG) as well as the Air Force Research Laboratory RITA program FA8750-16-2-0141. K.C.C. acknowledges funding support by the NSF Graduate Research Fellowships Program and ARL CDQI. M.P.W. acknowledges support from the NSF Center for Integrated Quantum Materials (CIQM), NSF Grant No. DMR-1231319. M.T. acknowledges support by an appointment to the Intelligence Community Postdoctoral Research Fellowship Program at the Massachusetts Institute of Technology, administered by the Oak Ridge Institute for Science and Education through an interagency agreement between the US DOE and the Office of the Director of National Intelligence. L.D.S would like to acknowledge support from the Under Secretary of Defense for Research and Engineering administered through the MIT Lincoln Laboratory Technology