Simultaneous thermometry and magnetometry using a fiber-coupled quantum diamond sensor

Abstract

Energy conservation and battery life extension are key challenges for the next-generation hybrid electric vehicles. In particular, the temperature and electric currents in a storage battery need to be monitored simultaneously with ∼1 kHz signal bandwidth for optimum battery usage. Here we introduce a centimeter-scale portable quantum sensor head, consisting of a diamond substrate hosting an ensemble of nitrogen-vacancy (NV) color centers with a density of ∼3 × 1017 cm−3. One diamond surface is attached to a multi-mode fiber for simultaneous optical excitation and readout of the NV centers, while the other diamond surface is attached to a coplanar microwave guide for NV spin ground-state mixing. Signal bandwidth of 1 kHz was realized through time-domain multiplexing of the two-tone microwave frequency modulation at 20 kHz. Two microwave frequencies were locked to the two resonance points that were determined from the optically detected magnetic resonance spectrum. From the mean and the difference of the deviation from the two locked frequencies, the temperature and magnetic field were obtained simultaneously and independently, with sensitivities of 3.5 nT/Hz1/2 and 1.3 mK/Hz1/2, respectively. We also showed that our sensor reached a minimum detectable magnetic field of 5 pT by accumulating signals for over 10 000 s.

High-precision robust monitoring of charge/discharge current over a wide dynamic range for electric vehicle batteries using diamond quantum sensors

“…2 received 100 mW excitation light. The fluorescence collection efficiency was ~ 1% 22 . Methods to improve fluorescence collection with lenses 6 or surface coating 9 will certainly improve the efficiency, and improving the fluorescence collection efficiency by a factor of N will reduce the excitation light power by 1/N.…”

Diamond quantum thermometry: From foundations to applications

“…Measuring Allan variance data is important to determine the appropriate integration time [83,[117][118][119]. Figure 6 with a slope of −0.35 is speculated to have originated from the mechanical instability of the microscope.…”

Temperature Fluctuations Compensation with Multi-Frequency Synchronous Manipulation for a NV Magnetometer in Fiber-Optic Scheme

“…Based on the optical excitation and detection of the NV center, the techniques have significant potential in terms of volume and sensitivity when forming a fiber magnetic field sensor [ 4 , 5 ]. At present, nanodiamond and bulk diamond have achieved intracellular measurement and electromagnetic imaging combined with fiber, and an NV magnetometer in fiber-optic scheme has been developed with high resolution and high stability [ 6 , 7 , 8 ].…”

“…Y. Hatano introduced a centimeter-scale portable quantum sensor head-in-fiber scheme. A continuous measuring mode is adopted to analyze the temperature noise from the magnetic field spectrum and to test long-term stability under a magnetic shielding condition in a laboratory environment [ 6 ]. For miniaturized, portable fiber magnetometers, the compact application scenarios make it difficult to diffuse the heat generated by the measurement system or the biochemical process in living organisms, and adaptive in situ compensation methods for temperature drift are particularly needed [ 16 ].…”