AI 中文总结
该研究提出脉冲探针读出方案，结合周期性探测等方法，实现高密度钾蒸汽池光学量子传感器的关联自旋噪声抑制，助力其接近自旋噪声极限，可应用于射频磁力测量等领域。
AI 中文摘要
基于碱金属原子的光学量子传感器可在室温下实现高灵敏度的磁场测量，一旦技术噪声源被充分抑制，其最终性能会受到固有自旋噪声的限制。因此，降低并表征这种噪声对于提高传感器灵敏度和研究量子增强传感协议至关重要。本研究利用脉冲探针读出方案，对基于高密度钾蒸汽池的射频光学量子传感器中的关联自旋涨落进行了研究。该系统采用正交的泵浦光和探针光束，而静磁场则确定传感频率并使探针脉冲与自旋进动同步。为检测弱自旋关联，研究人员实现了一种结合周期性探测、相位循环和窗口偏移采集的测量协议：相位循环可抑制可重复的探针诱导相干瞬态，而对自旋弛豫时间内采集的时间关联信号进行相减，可降低测得的自旋噪声水平。观测到的噪声抑制与时间自旋关联（包括自旋压缩协议中预期的关联）一致，不过当前测量无法将该解释与其他关联噪声机制明确区分。所展示的测量协议为使暖蒸汽光学量子传感器接近其基本自旋噪声极限提供了实用途径，可能有益于射频磁力测量和弱相干信号的传感，包括新兴的暗物质探测方案。
英文摘要
Optical quantum sensors based on alkali-metal atoms enable highly sensitive magnetic-field measurements at room temperature. Their ultimate performance is limited by intrinsic spin noise once technical noise sources are sufficiently suppressed. Reducing and characterizing this noise is therefore essential for improving sensor sensitivity and for investigating quantum-enhanced sensing protocols. Here we investigate correlated spin fluctuations in a radio-frequency optical quantum sensor based on a high-density potassium vapor cell using a pulsed probe readout scheme. The system employs orthogonal pump and probe laser beams, while a static magnetic field defines the sensing frequency and synchronizes the probe pulses with the spin precession. To detect weak spin correlations, we implement a measurement protocol that combines periodic probing, phase cycling, and window-shifted acquisition. Phase cycling suppresses reproducible probe-induced coherent transients, while subtraction of temporally correlated signals acquired within the spin-relaxation time reduces the measured spin-noise level. The observed noise reduction is consistent with temporal spin correlations, including those expected in spin-squeezing protocols, although the present measurements do not uniquely distinguish this interpretation from other correlated-noise mechanisms. The demonstrated measurement protocol provides a practical route toward operating warm-vapor optical quantum sensors closer to their fundamental spin-noise limit and may benefit radio-frequency magnetometry and sensing of weak coherent signals, including emerging dark-matter detection schemes.
