title: Repetitive readout of a single electronic spin via quantum logic with nuclear spin ancillae.
abstract: Robust 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.
authors.affiliation: Department of Physics, Harvard University, Cambridge, MA 02138, USA.
authors.forename: L
authors.initials: L
authors.lastname: Jiang
authors.forename: J S
authors.initials: JS
authors.lastname: Hodges
authors.forename: J R
authors.initials: JR
authors.lastname: Maze
authors.forename: P
authors.initials: P
authors.lastname: Maurer
authors.forename: J M
authors.initials: JM
authors.lastname: Taylor
authors.forename: D G
authors.initials: DG
authors.lastname: Cory
authors.forename: P R
authors.initials: PR
authors.lastname: Hemmer
authors.forename: R L
authors.initials: RL
authors.lastname: Walsworth
authors.forename: A
authors.initials: A
authors.lastname: Yacoby
authors.forename: A S
authors.initials: AS
authors.lastname: Zibrov
authors.forename: M D
authors.initials: MD
authors.lastname: Lukin