@article{oai:repo.qst.go.jp:00085693,
 author = {Zhang, Chen and Shagieva, Farida and Widmann, Matthias and Michael, Kübler and Vorobyov, Vadim and Kapitanova, Polina and Nenasheva, Elizaveta and Corkill, Ruth and Rhrle, Oliver and Nakamura, Kazuo and Sumiya, Hitoshi and Shinobu, Onoda and Junichi, Isoya and Jörg, Wrachtrup and Shinobu, Onoda and Junichi, Isoya},
 issue = {6},
 journal = {PHYSICAL REVIEW APPLIED},
 month = {Jun},
 note = {Nitrogen-vacancy (N-V) centers in diamond have developed into a powerful solid-state platform for compact quantum sensors. However, high-sensitivity measurements usually come with additional constraints on the pumping intensity of the laser and the pulse control applied. Here, we demonstrate high-sensitivity N-V-ensemble-based magnetic field measurements with low-intensity optical excitation. Direct current magnetometry methods such as continuous-wave optically detected magnetic resonance and continuously excited Ramsey measurements combined with lock-in detection are compared to achieve an optimization. Gradiometry is also investigated as a step towards unshielded measurements of unknown gradients. The magnetometer demonstrates a minimum detectable field of 0.3–0.7 pT in a 73-s measurement when a flux guide with a sensing dimension of 2 mm is applied, corresponding to a magnetic field sensitivity of 2.6–6 pT/√Hz. Combined with our previous efforts on diamond ac magnetometry, the diamond magnetometer is promising for performing wide-bandwidth magnetometry with picotesla sensitivity and a cubic-millimeter sensing volume under ambient conditions.},
 title = {Diamond Magnetometry and Gradiometry Towards Subpicotesla dc Field Measurement},
 volume = {15},
 year = {2021}
}