With the help of Stokes operator Ŝ₂ squeezed state (also called polarization squeezed state (PSS)) of 795 nm light, rubidium-87 (⁸⁷Rb) atomic magnetometer based on Faraday rotation (FR) has been implemented and characterized. The PSS of Stokes operator Ŝ₂ of 795 nm light has been prepared by means of coherently combining the polarization coherent state (PCS) of a linearly p-polarized bright 795 nm light beam and a linearly s-polarized squeezed vacuum state (SVS) generated by a 397.5 nm ultraviolet laser pumped sub-threshold optical parametric oscillator (OPO) with a PPKTP bulk crystal inside the OPO cavity. PSS with a squeezing level of −3.7 0.3 dB has been achieved around the analysis frequency of 10 kHz. At different transitions of D₁ line, various frequency detuning, and reasonable atomic vapor cell’s temperature, FR has been measured and compared. To decrease absorption (scattering) losses and the back-action from atomic spin noise to the probe beam’s polarization noise for maintaining the quantum properties of PSS of Stokes operator Ŝ₂ of 795 nm light, we had to run our magnetometer with ⁸⁷Rb vapor cell’s temperature below 60 C, at which the PSS was almost destroyed. The sensitivities of magnetic field measurement were characterized via measuring signal-to-noise ratio of the alternating current calibrated magnetic field signal with a balanced polarimeter. Under the conditions of the atomic number density of ∼5.8 10¹⁰ cm⁻³ (T ∼ 40 C) and the probe beam with a detuning of ∼−400 MHz relative to the 5S_1/2 (F _g = 2) − 5P_1/2 (F _e = 1) transition of ⁸⁷Rb D₁ line, a typical sensitivity of ∼19.5 pT (Hz^1/2)⁻¹ has been achieved employing PSS of Stokes operator Ŝ₂ as the probe, compared with a sensitivity of ∼28.3pT (Hz^1/2)⁻¹ using PCS as the probe. We preliminarily demonstrated that the quantum-enhanced sensitivity in a Faraday-rotation-based ⁸⁷Rb atomic magnetometer with the help of PSS of 795 nm light.

在795 nm 光的 Stokes 算子Ŝ ₂ 挤压态（也称为偏振挤压态 (PSS)）的帮助下，基于法拉第旋转 (FR) 的铷 87 ( ⁸⁷ Rb) 原子磁强计已被实现和表征。Stokes 算子的 PSS Ŝ ₂ 通过将线性 p 偏振亮 795 nm 光束的偏振相干态 (PCS) 和由 397.5 nm 紫外激光泵浦产生的线性 s 偏振压缩真空态 (SVS) 相干组合，制备了 795 nm 光亚阈值光学参量振荡器 (OPO)，在 OPO 腔内具有 PPKTP 块状晶体。已在 10 kHz 的分析频率附近实现了压缩电平为 -3.7 0.3 dB 的 PSS。在D ₁线的不同跃迁、各种频率失谐以及合理的原子蒸气室温度下，测量并比较了FR。减少吸收（散射）损失和从原子自旋噪声到探测光束偏振噪声的反作用，以保持斯托克斯算子的 PSS 的量子特性Ŝ 795 nm 光中的_{2 个}，我们不得不在⁸⁷ Rb 蒸气池的温度低于 60 C 的情况下运行我们的磁力计，在该温度下 PSS 几乎被破坏。磁场测量的灵敏度是通过用平衡旋光仪测量交流校准磁场信号的信噪比来表征的。在原子序数密度为 ~5.8 10 ¹⁰ cm ^-3 ( T ~ 40 C) 和探测光束相对于 5S _1/2 ( F _g = 2) − 5P ₁失谐为 ~-400 MHz 的条件下_/2 ( F _e = 1) ⁸⁷ Rb D _{1 的}跃迁线，使用 Stokes 算子Ŝ _{2 的}PSS作为探针实现了 ∼19.5 pT (Hz ^1/2 ) ^-1的典型灵敏度，而使用 PCS 作为探针的灵敏度为 ∼28.3pT (Hz ^1/2 ) ^-1探头。我们在795 nm 光 PSS 的帮助下初步证明了基于法拉第旋转的⁸⁷ Rb 原子磁强计的量子增强灵敏度。