title: Quantum entanglement at ambient conditions in a macroscopic solid-state spin ensemble.
abstract: Entanglement is a key resource for quantum computers, quantum-communication networks, and high-precision sensors. Macroscopic spin ensembles have been historically important in the development of quantum algorithms for these prospective technologies and remain strong candidates for implementing them today. This strength derives from their long-lived quantum coherence, strong signal, and ability to couple collectively to external degrees of freedom. Nonetheless, preparing ensembles of genuinely entangled spin states has required high magnetic fields and cryogenic temperatures or photochemical reactions. We demonstrate that entanglement can be realized in solid-state spin ensembles at ambient conditions. We use hybrid registers comprising of electron-nuclear spin pairs that are localized at color-center defects in a commercial SiC wafer. We optically initialize 10(3) identical registers in a 40-μm(3) volume (with [Formula: see text] fidelity) and deterministically prepare them into the maximally entangled Bell states (with 0.88 ± 0.07 fidelity). To verify entanglement, we develop a register-specific quantum-state tomography protocol. The entanglement of a macroscopic solid-state spin ensemble at ambient conditions represents an important step toward practical quantum technology.
authors.affiliation: Institute for Molecular Engineering, University of Chicago, Chicago, IL 60637, USA. ; Department of Physics, University of California, Santa Barbara, CA 93106, USA.
authors.forename: Paul V
authors.initials: PV
authors.lastname: Klimov
authors.affiliation: Institute for Molecular Engineering, University of Chicago, Chicago, IL 60637, USA. ; IBM T. J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, NY 10598, USA.
authors.forename: Abram L
authors.identifier: 0000-0002-5531-2891
authors.initials: AL
authors.lastname: Falk
authors.affiliation: Institute for Molecular Engineering, University of Chicago, Chicago, IL 60637, USA. ; Department of Physics, University of California, Santa Barbara, CA 93106, USA.
authors.forename: David J
authors.identifier: 0000-0001-9338-3335
authors.initials: DJ
authors.lastname: Christle
authors.affiliation: Ames Laboratory and Iowa State University, Ames, IA 50011, USA.
authors.forename: Viatcheslav V
authors.initials: VV
authors.lastname: Dobrovitski
authors.affiliation: Institute for Molecular Engineering, University of Chicago, Chicago, IL 60637, USA.
authors.forename: David D
authors.initials: DD
authors.lastname: Awschalom
keywords: hybrid quantum systems; macroscopic quantum phenomena; nuclear spintronics; optically detected magnetic resonance; quantum entanglement; quantum information processing; quantum sensing; room-temperature quantum phenomena; spintronics