Enhancing weak-magnetic-field sensing of a cavity-magnon system with dual frequency modulation
Zheng Liu, Yu‐qiang Liu, Z.H. Mai, Yi‐jia Yang, Nannan Zhou, Chang‐shui Yu
Abstract
The crucial limitation of improving the sensitivity of the detection of weak magnetic fields is the unavoidable measurement noise. In this paper, we propose a scheme to achieve precise sensing robust against additional noise by employing a dual frequency bias field modulation within a cavity-magnon system. We find that the antirotating wave term can amplify the signal of the detected magnetic field, but this amplification effect must coexist with the rotating wave term. In particular, by the bias field modulation, we find the robustness against cavity field thermal noise is substantially enhanced, quantum noise and cavity field thermal noise is greatly reduced, and the external magnetic field signal is amplified, thereby improving the weak-magnetic-field sensing system's sensitivity. Compared with the previous scheme, our scheme requires neither an ultrastrong- or deep-strong-coupling mechanism nor the suppression of the additional noise by increasing the electromagnetic cooperativity. Our scheme could provide a valuable candidate for weak-magnetic-field sensing.