Jiang, LiangHodges, J. S.Maze, J. R.Maurer, Peter ChristianTaylor, J. M.Cory, D. G.Hemmer, P. R.Walsworth, RonaldYacoby, AmirZibrov, AlexanderLukin, Mikhail2017-08-072009Jiang, L., J. S. Hodges, J. R. Maze, P. Maurer, J. M. Taylor, D. G. Cory, P. R. Hemmer, et al. 2009. “Repetitive Readout of a Single Electronic Spin via Quantum Logic with Nuclear Spin Ancillae.” Science 326 (5950) (September 10): 267–272. doi:10.1126/science.1176496.0036-8075http://nrs.harvard.edu/urn-3:HUL.InstRepos:33719344Robust measurement of single quantum bits plays a key role in the realization of quantum computation and communication as well as in quantum metrology and sensing. We have implemented a method for the improved readout of single electronic spin qubits in solid-state systems. The method makes use of quantum logic operations on a system consisting of a single electronic spin and several proximal nuclear spin ancillae in order to repetitively readout the state of the electronic spin. Using coherent manipulation of a single nitrogen vacancy center in room-temperature diamond, full quantum control of an electronic-nuclear system consisting of up to three spins was achieved. We took advantage of a single nuclear-spin memory in order to obtain a 10-fold enhancement in the signal amplitude of the electronic spin readout. We also present a two-level, concatenated procedure to improve the readout by use of a pair of nuclear spin ancillae, an important step toward the realization of robust quantum information processors using electronic- and nuclear-spin qubits. Our technique can be used to improve the sensitivity and speed of spin-based nanoscale diamond magnetometers.en-USJournal Article10.1126/science.1176496