A scheme of an ultrasensitive magnetometer in the cavity quantum electromagnonics is proposed, where the intracavity microwave mode is coupled to a magnonic mode via magnetic dipole interaction. It is shown that by driving both magnonic and microwave modes with external classical fields and controlling the system parameters, one can reduce the added noise of magnetic field measurement below the standard quantum limit (SQL). Surprisingly, we show that beyond the rotating wave approximation (RWA), not only can the added noise be suppressed but also the output cavity response to the input signal can be substantially amplified in order to achieve a precise magnetic-field measurement. The estimated theoretical sensitivity of the proposed magnetic amplifier-sensor is approximately on the order of ${10}^{-18}\mathrm{T}/\sqrt{\mathrm{Hz}}$, which is competitive compared to the current state-of-the-art magnetometers like superconducting quantum interference devices (SQUIDs) and atomic magnetometers. The advantages of the proposed sensor in comparison with the other magnetometers is its high sensitivity at room temperature, sensing in a wide range of frequencies up to MHz, and its capability for signal-response amplification.

中文翻译：

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腔电磁学中的单正交量子磁力测量

提出了一种腔内量子电磁学中超灵敏磁力计的方案，其中腔内微波模式通过磁偶极子相互作用耦合到磁子模式。结果表明，通过用外部经典场驱动磁子和微波模式并控制系统参数，可以将磁场测量的附加噪声降低到标准量子极限（SQL）以下。令人惊讶的是，我们表明，除了旋转波近似 (RWA)，不仅可以抑制增加的噪声，而且可以显着放大对输入信号的输出腔响应，以实现精确的磁场测量。所提出的磁放大器传感器的估计理论灵敏度大约为${10}^{-18}\mathrm{吨}/\sqrt{\mathrm{赫兹}}$，与当前最先进的磁力计（如超导量子干涉装置 (SQUID) 和原子磁力计）相比，具有竞争力。与其他磁力计相比，所提出的传感器的优势在于其在室温下的高灵敏度、高达 MHz 的宽频率范围的感测以及信号响应放大的能力。