Systematic nonuniform field effects in miniature atomic co-magnetometers

Wafer-fabricated vapor cells are essential components in the development of scalable, field-deployable atomic sensing systems, including atomic spin gyroscopes (ASGs). This paper presents a systematic study of magnetic resonance spectra obtained in a two-chamber, millimeter-sized, wafer-fabricated cell containing Cs, 129Xe, 131Xe, and N2 buffer gas. For a range of vapor temperatures and pump powers, we identify characteristic structural and dynamical effects, including electric quadrupole splitting of the 131Xe frequency and spectral branching of the 129Xe frequency and linewidth as the signature of a parity-time symmetry-broken phase. Remarkably, we demonstrate that a primary class of systematic nonuniform field effects can be reduced to a simple one-dimensional linear gradient. We leverage these effects to offer regimes of optimized and robust sensor operation, setting a benchmark for the performance of wafer-fabricated vapor cells in both ASGs and more broad quantum technologies.