We show that electric field noise from surface charge fluctuations can be a significant source of spin decoherence for near-surface nitrogen-vacancy (NV) centers in diamond. This conclusion is based on the increase in spin coherence observed when the diamond surface is covered with high-dielectric-constant liquids, such as glycerol. Double resonance experiments show that improved coherence occurs even though the coupling to nearby electron spins is unchanged when the liquid is applied. Multipulse spin echo experiments reveal the effect of glycerol on the spectrum of NV frequency noise.
Magnetic field sensitivity and decoherence spectroscopy of an ensemble of narrow-linewidth nitrogen-vacancy centers close to a diamond surface
我们进行脉冲光学检测电子自旋共振测量的直流磁场灵敏度和电子自旋相干时间T_2的近表面，高密度氮空位（NV）中心设计有一个狭窄的磁共振线宽的合奏。将脉冲光谱与动态核极化相结合，获得了35 nT Hz^{-0.5}的光子散粒噪声限制的直流磁灵敏度。我们发现，T_2是由瞬时扩散控制，使退相干光谱的残留氮杂质自旋在金刚石晶格和定量测定其密度。所展示的高直流磁灵敏度和退相干光谱有望拓宽二维磁成像的应用范围。
Proton magnetic resonance imaging with a nitrogen-vacancy spin sensor
具有纳米分辨率的核磁共振（NMR）成像需要灵敏度远远超过传统感应检测能力的新检测技术。在这里，我们展示了二维成像的$^1$ H NMR从一个有机测试样品使用一个单一的氮空位中心的金刚石作为传感器。当样品扫描通过NV中心时，NV中心检测来自样品中旋进质子的振荡磁场。示出了12 nm的空间分辨率，其主要受扫描精度的限制。随着进一步的发展，NV检测的磁共振成像可能会成为复杂纳米结构（包括生物分子）三维成像的新工具。
In this paper, starting from a quantum master equation, we discuss the interaction between two negatively charged Nitrogen-vacancy color centers in diamond via exciton-polaritons propagating in a two-dimensional transition metal dichalcogenide layer in close proximity to a diamond crystal. We focus on the optical 1.945 eV transition and model the Nitrogen-vacancy color centers as two-level (artificial) atoms. We find that the interaction parameters and the energy levels renormalization constants are extremely sensitive to the distance of the Nitrogen-vacancy centers to the transition metal dic…
We demonstrate real-time magnetometry by detecting fluorescence from a nitrogen vacancy center in the setting of coherent population trapping and by estimating magnetic field from the time series of the observed photon counts, which are correlated with the underlying field. The proof-of-principle experiment uses an external time-varying magnetic field that follows an Ornstein-Uhlenbeck (OU) process. By taking into consideration the statistical properties of the OU process, a Bayesian inference-based estimator can effectively update dynamical information of the field in real time with the detec…
Fluorescent nanodiamonds containing negatively-charged nitrogen-vacancy (NV$^-$) centers are promising for a wide range of applications, such as for sensing, as fluorescence biomarkers, or to hyperpolarize nuclear spins. NV$^-$ centers are formed from substitutional nitrogen (P1 centers) defects and vacancies in the diamond lattice. Maximizing the concentration of NVs is most beneficial, which justifies the search for methods with a high yield of conversion from P1 to NV$^-$. We report here the characterization of surface cleaned fluorescent micro- and nanodiamonds, obtained by irradiation of …
The neutral charge state plays an important role in quantum information and sensing applications based on nitrogen-vacancy centers. However, the orbital and spin dynamics remain unexplored. Here, we use resonant excitation of single centers to directly reveal the fine structure, enabling selective addressing of spin-orbit states. Through pump-probe experiments, we find the orbital relaxation time (430ns at 4.7K) and measure its temperature-dependence up to 11.8K. Finally we reveal the spin relaxation time (1.5s), and realize projective high-fidelity single-shot readout of the spin state ($\geq…
Silicon carbide (SiC) has become a key player in realization of scalable quantum technologies due to its ability to host optically addressable spin qubits and wafer-size samples. Here, we have demonstrated optically detected magnetic resonance (ODMR) with resonant excitation, and clearly identified the ground state energy levels of the NV centers in 4H-SiC. Coherent manipulation of NV centers in SiC has been achieved with Rabi and Ramsey oscillations. Finally, we show the successful generation and characterization of single nitrogen vacancy (NV) center in SiC employing ion implantation. Our re…
We report a study of high-resolution microwave spectroscopy of nitrogen-vacancy centers in diamond crystals at and around zero magnetic field. We observe characteristic splitting and transition imbalance of the hyperfine transitions, which originate from level anti-crossings in the presence of a transverse effective field. We use pulsed electron spin resonance spectroscopy to measure the zero-field spectral features of single nitrogen-vacancy centers for clearly resolving such level anti-crossings. To quantitatively analyze the magnetic resonance behavior of the hyperfine spin transitions in t…
