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

Abstract

Controllable atomic-scale quantum systems hold great potential as sensitive tools for nanoscale imaging and metrology [1][2][3][4][5][6]. Possible applications range from nanoscale electric [7] and magnetic field sensing [4][5][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.The NV center in diamond is a point-defect that offers the potential for sensing and imaging with atomic scale resolution. Sensitive nanoscale detection of various physical quantities is possible because the NV center forms a bright and stable single photon source [13] for optical imaging, and possesses a spin-triplet ground state which offers excellent magnetic [5] and electric [7] field sensing capabilities. The remarkable performance of the NV center in such spin-based sensing schemes, is the result of the long NV spin coherence time [14], combined with efficient optical spin preparation and readout [15], all at room temperature. In addition, NV centers can be positioned within nanometers of a diamond surface [16] and therefore in close proximity of a sample to maximize signal strengths and spatial resolution. In order to realize the full potential of these attractive features, we have developed a "scanning NV sensor" (Fig. 1a), which employs a diamond nanopillar as the scanning probe, with an individual NV center artificially created within a few nanometers of the pillar tip through ion implantation. Long NV spin coherence times (≈ 30 µs) are achieved as our devices are fabricated from high purity, single-crystalline bulk diamond [17]. Furthermore, diamond nanopillars are efficient waveguides for the NV fluorescence band [18], which yields record-high NV signal collection efficiencies for a scanning NV device. Fig. 1b shows a representative scanning electron microscope (SEM) image of a single-crystalline diamond scanning probe containing a single NV center. The preparation of such devices is based on recently developed tech- * These authors contributed equally to this work...

Suppression of spin-bath dynamics for improved coherence of multi-spin-qubit systems

“…Such optimization, along with spectral decomposition studies of samples with varying 13 C concentrations, at low temperatures and at high magnetic fields, will be pursued in future work. The present results, together with the possibility of single qubit addressability through AFM [39][40][41] or super-resolution optical techniques 42 and intrinsic qubit-qubit interactions 1 , pave the way for quantum information, sensing and metrology applications in a robust, multi-qubit solid-state architecture. Finally, the spectral decomposition technique presented here, based on well-known pulse sequences and a simple reconstruction algorithm, can be applied to other composite solid-state spin systems, such as quantum dots and phosphorous donors in silicon.…”

Relaxometry and Dephasing Imaging of Superparamagnetic Magnetite Nanoparticles Using a Single Qubit

“…This arrangement is conceptually equivalent 14 to an NV center being fixed to a scanning probe tip as is commonly used for imaging of DC magnetic fields 9,21 . Here, the sample is made of superparamagnetic magnetite nanoparticles (diameter: 8±3 nm, see Supp.…”

Magnetic spin imaging under ambient conditions with sub-cellular resolution

“…Precision metrology has already been demonstrated for DC and AC fields [9][10][11][12][13][14] , spins within the diamond lattice [15][16][17][18] and surface spins 19 . Here, we demonstrate sensing and imaging of stochastic magnetic fluctuations originating from freely diffusing electron spins such as paramagnetic oxygen (O 2 , S ¼ 1), MnCl 2 (S ¼ 5/2) and Gadolinium ions (Gd 3 þ , S ¼ 7/2) in liquids, immobilized in polymers and linked specifically to cellular structures.…”