Picotesla fiberized diamond-based AC magnetometer

Portable quantum sensors are crucial for developing practical quantum sensing and metrology applications.Fiberized nitrogen-vacancy(NV)centers in diamonds have emerged as one of the most promising candidates for compact quantum sensors.Nevertheless,due to the difficulty of coherently controlling the ensemble spin and noise suppression in a large volume,it often faces problems such as reduced sensitivity and narrowed bandwidth in integrated lensless applications.Here,we propose a fluorescence signal treatment method for NV spin ensemble manipulation by the exponential fitting of spin polarization processes,instead of integrating the photon emission.This enables spin state readout with a high signal-to-noise ratio and applies to the pulse sensing protocols for large-volume NV spins.Based on this,we further developed a fiberized diamond-based AC magnetometer.With an XY8-N dynamical decoupling pulse sequence,we demonstrated a T_(2)-limited sensitivity of 8pT/√Hz and T_(1)-limited frequency resolution of 90 Hz over a wide frequency band from 100 kHz to 3 MHz.This integrated diamond sensor leverages quantum coherence to achieve enhanced sensitivity in detecting AC magnetic fields,making it suitable for implementation in a compact and portable endoscopic sensor.

High-sensitivity and wide-bandwidth fiber-coupled diamond magnetometer with surface coating

Mapping magnetic fields from different materials and structures can provide a powerful means for broad applications of activity probe and feature analysis.Here,we present a high-sensitivity and wide-bandwidth fiber-based quantum magnetometer at the scale of a few hundred micrometers.We propose a fiber-coupled diamond magnetometer.Tracking a pulsed optically detected magnetic resonance spectrum allows a magnetic field sensitivity of 103 pT∕■and a bandwidth of 2.6 k Hz.Additionally,with an approach of coating the diamond surface with silver reflective film,both the fluorescence collection and excitation efficiency are significantly enhanced,and the sensitivity and bandwidth are expected to be further improved to 50 pT∕■and 4.1 k Hz,respectively.Finally,this fiber-based quantum magnetometer is applied as a probe to successfully map the magnetic field induced by the current-carrying copper-wire mesh.Such a stable and compact magnetometer can provide a powerful tool in many areas of physical,chemical,and biological researches.