title: Readout and control of a single nuclear spin with a metastable electron spin ancilla.
abstract: Electron and nuclear spins associated with point defects in insulators are promising systems for solid-state quantum technology. The electron spin is usually used for readout and addressing, and nuclear spins are used as exquisite quantum bits and memory systems. With these systems, single-shot readout of single nuclear spins as well as entanglement, aided by the electron spin, have been shown. Although the electron spin in this example is essential for readout, it usually limits the nuclear spin coherence, leading to a quest for defects with spin-free ground states. Here, we isolate a hitherto unidentified defect in diamond and use it at room temperature to demonstrate optical spin polarization and readout with exceptionally high contrast (up to 45%), coherent manipulation of an individual excited triplet state spin, and coherent nuclear spin manipulation using the triplet electron spin as a metastable ancilla. We demonstrate nuclear magnetic resonance and Rabi oscillations of the uncoupled nuclear spin in the spin-free electronic ground state. Our study demonstrates that nuclei coupled to single metastable electron spins are useful quantum systems with long memory times, in spite of electronic relaxation processes.
authors.affiliation: Physikalisches Institut and Research Center SCOPE, University Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany.
authors.forename: Sang-Yun
authors.initials: SY
authors.lastname: Lee
authors.forename: Matthias
authors.initials: M
authors.lastname: Widmann
authors.forename: Torsten
authors.initials: T
authors.lastname: Rendler
authors.forename: Marcus W
authors.initials: MW
authors.lastname: Doherty
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Babinec
authors.forename: Sen
authors.initials: S
authors.lastname: Yang
authors.forename: Moritz
authors.initials: M
authors.lastname: Eyer
authors.forename: Petr
authors.initials: P
authors.lastname: Siyushev
authors.forename: Birgit J M
authors.initials: BJ
authors.lastname: Hausmann
authors.forename: Marko
authors.initials: M
authors.lastname: Loncar
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Bodrog
authors.forename: Adam
authors.initials: A
authors.lastname: Gali
authors.forename: Neil B
authors.initials: NB
authors.lastname: Manson
authors.forename: Helmut
authors.initials: H
authors.lastname: Fedder
authors.forename: Jörg
authors.initials: J
authors.lastname: Wrachtrup