Michael Grinolds

A robust scanning diamond sensor for nanoscale imaging with single nitrogen-vacancy centres

Controllable atomic-scale quantum systems hold great potential as sensitive tools for nanoscale imaging and metrology [1–6]. Possible applications range from nanoscale electric [7] and magnetic field sensing [4–6, 8] to single photon microscopy [1, 2], quantum information processing [9], and bioimaging [10]. At the heart of such schemes is the ability to scan and accurately position a robust sensor within a few nanometers of a sample of interest, while preserving the sensor’s quantum coherence and readout fidelity. These combined requirements remain a challenge for all existing approaches that rely on direct grafting of individual solid state quantum systems [4, 11, 12] or single molecules [2] onto scanning-probe tips. Here, we demonstrate the fabrication and room temperature operation of a robust and isolated atomic-scale quantum sensor for scanning probe microscopy. Specifically, we employ a high-purity, single-crystalline diamond nanopillar probe containing a single Nitrogen-Vacancy (NV) color center. We illustrate the versatility and performance of our scanning NV sensor by conducting quantitative nanoscale magnetic field imaging and near-field single-photon fluorescence quenching microscopy. In both cases, we obtain imaging resolution in the range of 20 nm and sensitivity unprecedented in scanning quantum probe microscopy.

Nanoscale magnetic imaging of a single electron spin under ambient conditions

A magnetometer focused on nitrogen-vacancy centres in diamond can image the magnetic dipole field of a single target electron spin at room temperature and ambient pressure.

Quantum control of proximal spins using nanoscale magnetic resonance imaging

Single electron spins have been detected before, but the methods used proved difficult to extend to multi-spin systems. A magnetic resonance imaging technique is now demonstrated that resolves proximal spins in three dimensions with nanometre-scale resolution. In addition to spatial mapping, the approach allows for coherent control of the individual spins.

Coherent, Mechanical Control of a Single Electronic Spin

We demonstrate coherent quantum control of a single spin driven by the motion of a mechanical resonator. The motion of a mechanical resonator is magnetically coupled to the electronic spin of a single nitrogen-vacancy center in diamond. Synchronization of spin-addressing protocols to the motion of the driven oscillator is used to fully exploit the coherence of this hybrid mechanical-spin system. We demonstrate applications of this coherent mechanical spin-control technique to nanoscale scanning magnetometry.

Decoherence imaging of spin ensembles using a scanning single-electron spin in diamond

The nitrogen-vacancy (NV) defect center in diamond has demonstrated great capability for nanoscale magnetic sensing and imaging for both static and periodically modulated target fields. However, it remains a challenge to detect and image randomly fluctuating magnetic fields. Recent theoretical and numerical works have outlined detection schemes that exploit changes in decoherence of the detector spin as a sensitive measure for fluctuating fields. Here we experimentally monitor the decoherence of a scanning NV center in order to image the fluctuating magnetic fields from paramagnetic impurities on an underlying diamond surface. We detect a signal corresponding to roughly 800 μB in 2 s of integration time, without any control on the target spins, and obtain magnetic-field spectral information using dynamical decoupling techniques. The extracted spatial and temporal properties of the surface paramagnetic impurities provide insight to prolonging the coherence of near-surface qubits for quantum information and metrology applications.

Scanning probe magnetometry and nanoscale magnetic resonance imaging using nitrogen-vacancy spins in diamond

We have developed a scanning nitrogen-vacancy center magnetometer with unprecedented sensitivity and spatial resolution, which operates under ambient conditions. Here we present measurements using such a magnetometer to magnetically image a single electron spin.