Nitrogen-vacancy (NV) color centers in diamond crystals exhibit unique quantum properties that make them suitable for a wide range of technlogical applications, including precise measurements of magnetic fields. NV centers have triplet ground and excited states, which undergo Zeeman splitting in a magnetic field and exhibit dynamics that allow the ground state to be polarized to the spin-zero state through optical pumping (Fig. 1. (Left)) [1]. The transition energy of the electron-spin magnetic sublevels can be directly measured using the method of optically detected magnetic resonance [2].
The aim of the work described here is to create a prototype device for high DC current stabilization. The basis of the device is NV magnetometry with a diamond containing NV centers as the probe for a feedback loop for a power supply (Fig. 1. right). This approach is significantly different from existing methods, because it offers a wide dynamic range, high sensitivity and measurement rate (bandwidth) allowing for a compact, energy efficient, lightweight device.
One of the key challenges for NV based magnetometers is achieving a high enough magnetic field sensitivity, in this case, to measure changes in the current flowing through a wire with a high enough accuracy. Therefore, optimal engineering design and power parameters play a major role in a successful implementation. The magnetic field sensitivity achieved in this work at the moment is 30nT/Hz1/2 for measurement frequencies above 90Hz (Fig. 2.), using 110mW laser power, 100mW microwave power and a dual-resonance modulation technique [3].
