Vector magnetometry in zero bias magnetic field using nitrogen-vacancy ensembles

The application of the vector magnetometry based on nitrogen-vacancy(NV)ensembles has been widely investigatedin multiple areas.It has the superiority of high sensitivity and high stability in ambient conditions with microscale spatialresolution.However,a bias magnetic field is necessary to fully separate the resonance lines of optically detected magneticresonance(ODMR)spectrum of NV ensembles.This brings disturbances in samples being detected and limits the rangeof application.Here,we demonstrate a method of vector magnetometry in zero bias magnetic field using NV ensembles.By utilizing the anisotropy property of fluorescence excited from NV centers,we analyzed the ODMR spectrum of NVensembles under various polarized angles of excitation laser in zero bias magnetic field with a quantitative numerical modeland reconstructed the magnetic field vector.The minimum magnetic field modulus that can be resolved accurately is downto~0.64 G theoretically depending on the ODMR spectral line width(1.8 MHz),and~2 G experimentally due to noisesin fluorescence signals and errors in calibration.By using 13C purified and low nitrogen concentration diamond combinedwith improving calibration of unknown parameters,the ODMR spectral line width can be further decreased below 0.5 MHz,corresponding to~0.18 G minimum resolvable magnetic field modulus.

Experimental investigation of vector static magnetic field detection using an NV center with a single first-shell ^(13)C nuclear spin in diamond

We perform a proof-of-principle experiment that uses a single negatively charged nitrogen–vacancy（NV） color center with a nearest neighbor ^13C nuclear spin in diamond to detect the strength and direction（including both polar and azimuth angles） of a static vector magnetic field by optical detection magnetic resonance（ODMR） technique. With the known hyperfine coupling tensor between an NV center and a nearest neighbor ^13C nuclear spin, we show that the information of static vector magnetic field could be extracted by observing the pulsed continuous wave（CW） spectrum.

Estimation of vector static magnetic field by a nitrogen-vacancy center with a single first-shell ^(13)C nuclear(NV–^(13)C)spin in diamond

We suggest an experimental scheme that a single nitrogen-vacancy（NV） center coupled to a nearest neighbor ^13C nucleus as a sensor in diamond can be used to detect a static vector magnetic field. By means of optical detection magnetic resonance（ODMR） technique, both the strength and the direction of the vector field could be determined by relevant resonance frequencies of continuous wave（CW） and Ramsey spectrums. In addition, we give a method that determines the unique one of eight possible hyperfine tensors for an（NV–^13C） system. Finally, we propose an unambiguous method to exclude the symmetrical solution from eight possible vector fields, which correspond to nearly identical resonance frequencies due to their mirror symmetry about ^14N–Vacancy–^13 C（^14N–V–^13C） plane.

Spin-manipulated nanoscopy for single nitrogenvacancy center localizations in nanodiamonds

Due to their exceptional optical and magnetic properties,negatively charged nitrogen-vacancy(NV−)centers in nanodiamonds(NDs)have been identified as an indispensable tool for imaging,sensing and quantum bit manipulation.The investigation of the emission behaviors of single NV−centers at the nanoscale is of paramount importance and underpins their use in applications ranging from quantum computation to super-resolution imaging.Here,we report on a spin-manipulated nanoscopy method for nanoscale resolutions of the collectively blinking NV−centers confined within the diffraction-limited region.Using wide-field localization microscopy combined with nanoscale spin manipulation and the assistance of a microwave source tuned to the optically detected magnetic resonance(ODMR)frequency,we discovered that two collectively blinking NV−centers can be resolved.Furthermore,when the collective emitters possess the same ground state spin transition frequency,the proposed method allows the resolving of each single NV−center via an external magnetic field used to split the resonant dips.In spin manipulation,the three-level blinking dynamics provide the means to resolve two NV−centers separated by distances of 23 nm.The method presented here offers a new platform for studying and imaging spin-related quantum interactions at the nanoscale with superresolution techniques.