Accessing magnetic fields with dual-channel weak measurements

As a promising candidate for precision quantum metrology, recently, quantum weak measurement assisted magnetometers have shown potential advantage in enhancing sensitivity to small polarization changes. In this Letter, we propose a quantum weak measurement scheme for atomic magnetometers. To successfully address the challenges of both multi-parameter disturbance and high-frequency signal detection, a strategy of dual-channel weak measurement is employed in our experimental design. Our experimental data show clear improvement of the sensitivity in both DC and AC magnetic field detection. A deliberate comparison between our dual-channel weak measurement and the balanced detection scheme when subjected to the same experimental conditions shows that a much higher sensitivity is achieved in the dual-channel scheme, and an improvement of one order of magnitude is confirmed in the experiment.