Araújo Michelle O, Marinho Lucas S, Felinto Daniel
Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife, Pernambuco, Brazil.
Phys Rev Lett. 2022 Feb 25;128(8):083601. doi: 10.1103/PhysRevLett.128.083601.
We report the experimental verification of nonclassical correlations for an unfiltered spontaneous four-wave mixing process in an ensemble of cold two-level atoms, confirming theoretical predictions by Du et al. in 2007 for the violation of a Cauchy-Schwarz inequality in the system, and obtaining R=(1.98±0.03)≰1. Quantum correlations are observed in a nanoseconds timescale in the interference between the central exciting frequency and sidebands dislocated by the detuning to the atomic resonance. They prevail over the noise background coming from Rayleigh scattering from the same optical transition. These correlations are fragile with respect to processes that disturb the phase of the atomic excitation, but are robust to variations in number of atoms and to increasing light intensities.
我们报告了在冷二能级原子系综中未滤波的自发四波混频过程的非经典关联的实验验证，证实了Du等人在2007年关于该系统违反柯西 - 施瓦茨不等式的理论预测，并得到R =(1.98±0.03)≰1。在中心激发频率与因失谐至原子共振而错位的边带之间的干涉中，在纳秒时间尺度上观察到量子关联。它们优于来自相同光学跃迁的瑞利散射产生的噪声背景。这些关联对于干扰原子激发相位的过程很脆弱，但对于原子数的变化和光强的增加具有鲁棒性。
