Figure 3: Measurement of in situ magnetometer signal enhancement.

(a) ¹²⁹Xe NMR signals in the in situ (blue) and ex situ (red) magnetometer chambers. Inset: Zoom-in of the ex situ magnetometer signal, averaged 4096 times. In all cases, the pump chamber was maintained at a temperature of 140 °C and an optical pumping power of 70 mW was employed. A gas mixture consisting of 800 Torr Xe at natural isotopic abundance (26.4% ¹²⁹Xe) and 800 Torr N₂ was flowed through the device at a rate of 5 μL s⁻¹. The magnetometer chambers were maintained at a temperature of 110 °C and an optical power of 100 μW was employed in each magnetometer chamber. (b) Geometry of device combining in situ and ex situ magnetometry modalities. The ex situ magnetometer has dimensions identical to those of the in situ chamber and is separated from the gas flow by 1 mm of silicon in the y direction.