title: Single spin magnetic resonance.
abstract: Different approaches have improved the sensitivity of either electron or nuclear magnetic resonance to the single spin level. For optical detection it has essentially become routine to observe a single electron spin or nuclear spin. Typically, the systems in use are carefully designed to allow for single spin detection and manipulation, and of those systems, diamond spin defects rank very high, being so robust that they can be addressed, read out and coherently controlled even under ambient conditions and in a versatile set of nanostructures. This renders them as a new type of sensor, which has been shown to detect single electron and nuclear spins among other quantities like force, pressure and temperature. Adapting pulse sequences from classic NMR and EPR, and combined with high resolution optical microscopy, proximity to the target sample and nanoscale size, the diamond sensors have the potential to constitute a new class of magnetic resonance detectors with single spin sensitivity. As diamond sensors can be operated under ambient conditions, they offer potential application across a multitude of disciplines. Here we review the different existing techniques for magnetic resonance, with a focus on diamond defect spin sensors, showing their potential as versatile sensors for ultra-sensitive magnetic resonance with nanoscale spatial resolution.
authors.affiliation: 3. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany; Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany. Electronic address: wrachtrup@physik.uni-stuttgart.de.
authors.forename: Jörg
authors.initials: J
authors.lastname: Wrachtrup
authors.affiliation: 3. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany. Electronic address: a.finkler@physik.uni-stuttgart.de.
authors.forename: Amit
authors.initials: A
authors.lastname: Finkler
keywords: Electron spin resonance; Nitrogen-vacancy center in diamond; Nuclear magnetic resonance