Long spin-1/2 noble gas coherence times in mm-sized anodically bonded batch-fabricated ³He-¹²⁹Xe-⁸⁷Rb cells

As the only stable spin-1/2 noble gas isotopes, ³He and ¹²⁹Xe are promising systems for inertial rotation sensing and searches for exotic spin couplings. Spin-1/2 noble gases have intrinsic coherence times in the order of hours to days, which allows for incredibly low frequency error of free-precession measurements. However, relaxation in miniature cells is dominated by interactions with the cell wall, which limits the performance of a chip-scale sensor that uses noble gases. While ¹²⁹Xe wall relaxation times have previously been limited to 10s of seconds in mm-sized cells, we demonstrate the first anodically bonded batch-fabricated cells with dual ³He-¹²⁹Xe isotopes and ⁸⁷Rb in a 6 mm³ volume with ³He and ¹²⁹Xe T 2 coherence times of, respectively, 4 h and 300 s. We use these microfabricated cells in a dual noble gas comagnetometer and discuss its limits.