Freiburg 2019 – scientific programme
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FM: Fall Meeting
FM 41: Poster: Quantum Sensing
FM 41.9: Poster
Tuesday, September 24, 2019, 16:30–18:30, Tents
Sensitive DC magnetometry with nitrogen-vacancy center ensembles in diamond — •Chen Zhang1, Vadim Vorobyov1, Junichi Isoya2, and Jörg Wrachtrup1 — 13. Physikalisches Institut, Universität Stuttgart, Stuttgart, Germany — 2Research center for knowledge communities, University of Tsukuba, Japan
Negatively charged nitrogen vacancy (NV-) center ensembles in diamond has demonstrated a great potential with achieving a subpicotesla magnetic field sensitivity (T. Wolf, 2015), which makes it a competitive candidate for various applications in bio-sensing and brain-science. In order to take full advantages of the diamond magnetometer, the DC field sensitivity need to be further improved to meet the requirements. In this work, 13C purified diamonds with an extraordinary T2* time of 10 μs and T2 time of 200 μs were used, demonstrating a ~80 kHz continuous wave optically detected magnetic resonance (CW-ODMR) linewidth and ensuring the high DC sensitivity limit. A BaLn2Ti4O12 wide band MW resonator is used to provide homogeneous MW field for multi-frequency MW driving of all the hyperfine lines as well as NV- ensembles of different orientations (P. Kapitanova, 2018; C. Zhang, 2018), in order to improve the fluorescence contrast which is linearly related to the sensitivity limit. Balanced detection and lock-in amplifier are used to suppress optical fluctuation and to figure out the noise floor of the setup. By all the techniques we present, we are reaching a DC magnetic field sensitivity of 15 pT/Hz^(1/2) and targeting to 10 pT/Hz^(1/2), which could meet the basic requirement for the MEG signal sensing with a distance of 1 cm from the brain surface.