Quantum‐enhanced NMR Co‐Magnetometers Based on Encounter‐propagating Pump Beams

Abstract Nuclear Magnetic Resonance (NMR) co‐magnetometers are advanced quantum sensors capable of measuring angular velocity for inertial navigation. Within the Rb‐Xe atomic ensemble, Rb atoms absorb polarized light, decreasing electron spin polarization as the light travels greater distances. This attenuation causes a gradient in Rb spin polarization that severely affects atomic relaxation characteristics and degrades NMR sensors’ performance. Considering atomic diffusion motion, a theoretical simulation model is developed and the spatial distribution of electron spin polarization under the encounter‐propagating dual‐beam configuration is simulated. The simulation results demonstrate that the proposed dual‐beam scheme achieves a more uniform distribution of electron polarization within the atomic vapor cell. Experiments reveal an 18% enhancement in 129 Xe nuclear spin polarization using the dual‐beam scheme compared to the conventional single‐beam. Through the Fermi contact interaction between optically pumped Rb and Xe atoms, a more uniform spatial distribution of Rb spin polarization reduces the gradient relaxation of Xe atoms and its depolarization effects, thereby significantly enhancing the macroscopic Xe spin polarization and the signal‐to‐noise ratio (SNR) of NMR sensors. This study presents a new method for improving atomic polarization, significantly enhancing the performance of quantum sensors.