Nanoscale Sensing With Individual Nitrogen-Vacancy Centers in Diamond

Abstract

Nitrogen-vacancy (NV) centers in diamond have recently emerged as a promising new system for quantum information and nanoscale sensing applications. They have long coherence times at room temperature and can be positioned in proximity to the diamond surface, enabling magnetometry with high spatial resolution and coherent coupling to other quantum systems. This thesis presents three experiments in which single NV centers were used to sense magnetic fields at the nanometer scale. In the first experiment, the coherent evolution of a single NV spin is coupled to the motion of a magnetized mechanical resonator tens of nanometers from the NV. Coherent manipulation of the spin is used to sense the driven and Brownian motion of the resonator under ambient conditions, with picometer-scale sensitivity to motion. Future applications of this technique include the detection of the zero-point fluctuations of a mechanical resonator, the realization of strong spin-phonon coupling at a single quantum level, and the implementation of quantum spin transducers. In the second experiment, a single NV electronic spin is used to measure the quantum dynamics of distant individual nuclear spins from within a surrounding spin bath. The demonstrated sensing technique dramatically increases the potential size of NV based quantum registers for quantum information applications, and provides a new method for nanoscale magnetic resonance imaging of single nuclear spins. In the third experiment, single NV electronic spins are used to probe magnetic Johnson noise in the vicinity of conductive silver films. Measurements of polycrystalline silver films over a range of distances (20-200 nanometers) and temperatures (10-300 Kelvin) are consistent with the classically expected behavior of the magnetic fluctuations. However, Johnson noise is found to be dramatically suppressed next to single-crystal films, indicative of a substantial deviation from Ohm's law arising from the ballistic motion of the electrons in the metal. These result demonstrate that our technique provides a general, non-invasive probe of local electron transport in samples of arbitrary size and dimensionality, which can be used to explore materials response to localized impurities and the interplay between transport, interactions and disorder at the nanoscale.