旋进式铁磁针磁强计
A Precessing Ferromagnetic Needle Magnetometer
摘要：
预测铁磁针在其内禀自旋支配其旋转角动量$N\hbar \gg IΩ$的条件下以拉莫尔频率$Ω$绕磁场轴进动（$I$是针绕进动轴转动惯量，$N$是针中极化自旋的数量）。在该状态下，针表现为陀螺仪，其中自旋$N\hbar$通过结晶和形状各向异性沿针的易磁化轴保持。旋进铁磁针是一个由$N$自旋组成的关联系统，可以用来长时间测量磁场。原则上，通过利用量子不确定性的快速平均，旋进针磁力计的灵敏度可以远远超过基于气相中原子自旋旋进的磁力计。在来自与环境的耦合的噪声是次主导的条件下，量子和检测限制的磁力灵敏度的测量时间$t$的缩放是$t^{-3/2}$。铁磁针的进动现象可能对测试基础物理的精密测量特别感兴趣。
英文摘要：
A ferromagnetic needle is predicted to precess about the magnetic field axis at a Larmor frequency $Ω$ under conditions where its intrinsic spin dominates over its rotational angular momentum, $N\hbar \gg IΩ$ ($I$ is the moment of inertia of the needle about the precession axis and $N$ is the number of polarized spins in the needle). In this regime the needle behaves as a gyroscope with spin $N\hbar$ maintained along the easy axis of the needle by the crystalline and shape anisotropy. A precessing ferromagnetic needle is a correlated system of $N$ spins which can be used to measure magnetic fields for long times. In principle, by taking advantage of rapid averaging of quantum uncertainty, the sensitivity of a precessing needle magnetometer can far surpass that of magnetometers based on spin precession of atoms in the gas phase. Under conditions where noise from coupling to the environment is subdominant, the scaling with measurement time $t$ of the quantum- and detection-limited magnetometric sensitivity is $t^{-3/2}$. The phenomenon of ferromagnetic needle precession may be of particular interest for precision measurements testing fundamental physics.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
