Fig. 1. (a) Schematic of the experimental apparatus (P-polarizer, B-magnetic fields, BP-balanced homodyne detector, FFT-fast Fourier transform); (b) typical spin noise spectrum of ¹³³Cs in cell 1 (the laser is detuned Ω_D2 = + 600 MHz from the D2 transition (6²S_1/2 (F = 4) → 6²P_3/2). The temperature of atomic cell is 296 K. The laser power P = 500 μW. Magnetic field B = 5 G); (c) D2 line transition and ground-state hyperfine structure of ¹³³Cs. (a)自旋噪声谱的实验原理图(P是偏振片, B是外加磁场, Wollaston prism是沃拉斯顿棱镜, BP是平衡零拍探测器, FFT是快速傅里叶变换); (b)气室1中经典的¹³³Cs自旋噪声谱(激光失谐频率Ω_D2 = + 600 MHz于D2线(6²S_1/2 (F = 4) → 6²P_3/2), 原子气室温度T = 296 K, 激光功率P = 500 μW, 外加磁场B = 5 G); (c) ¹³³Cs的D2跃迁线和基态超精细结构

Fig. 2. Magnetic-field dependent spin noise spectrum in cell 1: (a) Spin noise spectrum (black lines) and fitting curve (red lines) versus the magnetic fields; (b) dependence of center frequency of spin noise spectrum on magnetic fields. The blue circles are the experimental data. The red line is the fitting curve. The laser is detuned Ω_D2 = + 600 MHz from the D2 transition (6²S_1/2(F = 4) → 6²P_3/2). The laser power P = 500 μW. The temperature of atomic cell is 296 K. 气室1中磁场相关的自旋噪声谱　(a)不同磁场下的自旋噪声谱(黑线)和拟合曲线(红线); (b)自旋噪声谱中心频率(蓝圆圈)与外场关系图, 以及拟合曲线(红线); 激光失谐频率Ω_D2 = + 600 MHz于D2线(6²S_1/2 (F = 4) → 6²P_3/2), 激光功率为P = 500 μW, 原子气室温度T = 296 K

Fig. 3. Detuning frequency dependent spin noise spectrum in cell 1: (a) Spin relaxation rate versus the detuning frequency; (b) total noise versus the detuning frequency. The laser is detuned from the D2 transition (6²S_1/2(F = 3) → 6²P_3/2). The laser power P = 500 μW. Magnetic field B = 15 G. The blue circles are the experimental data. The red line is the fitting curve. The temperature of atomic cell is 296 K. 气室1中自旋噪声谱的失谐频率依赖关系　(a)自旋弛豫速率与失谐频率的对应关系图; (b)总噪声与失谐频率的对应关系图; 激光失谐频率在D2线(6²S_1/2(F = 3) → 6²P_3/2)附近, 激光功率P = 500 μW, 外磁场B = 15 G, 实验数据为(蓝圆圈)和拟合曲线(红线), 原子气室温度T = 296 K

Fig. 4. The detuning frequency dependent spin noise spectrum in cell 2: (a) Spin relaxation rate versus the detuning frequency at T = 387 K; (b) spin relaxation rate versus the detuning frequency at T = 431 K; (c) total noise versus the detuning frequency at T = 387 K; (d) total noise versus the detuning frequency at T = 431 K. The laser is detuned from the D2 transition (6²S_1/2(F = 3) → 6²P_3/2). The laser power P = 5 mW. The blue circles are the experimental data, and the red line is the fitting curve. 气室2中自旋噪声谱的失谐频率依赖关系　(a) T = 387 K时自旋弛豫速率与失谐频率的关系; (b) T = 431 K时自旋弛豫速率与失谐频率的关系; (c) T = 387 K时总噪声与失谐频率的关系; (d) T = 431 K时总噪声与失谐频率的关系; 激光失谐频率在D2线(6²S_1/2(F = 3) → ²P_3/2)附近, 激光功率为P = 5 mW, 蓝圆圈表示实验数据, 红线为拟合曲线