Opt Lett. 2023 Jun 15;48(12):3323-3326. doi: 10.1364/OL.494369.
We report the enhancement of quantum correlations for biphotons generated via spontaneous four-wave mixing in an ensemble of cold two-level atoms. This enhancement is based on the filtering of the Rayleigh linear component of the spectrum of the two emitted photons, favoring the quantum-correlated sidebands reaching the detectors. We provide direct measurements of the unfiltered spectrum presenting its usual triplet structure, with Rayleigh central components accompanied by two peaks symmetrically located at the detuning of the excitation laser with respect to the atomic resonance. The filtering of the central component results in a violation of the Cauchy-Schwarz inequality to (4.8±1.0)≰1 for a detuning of 60 times the atomic linewidth, representing an enhancement by a factor of four compared with the unfiltered quantum correlations observed at the same conditions.
我们报告了通过冷二能级原子集体中的自发四波混频产生的双光子的量子相关性增强。这种增强是基于对两个发射光子的光谱的瑞利线性分量进行滤波，从而有利于到达探测器的量子相关边带。我们提供了未过滤光谱的直接测量，呈现出其通常的三重结构，其中瑞利中心分量伴随着两个峰值，对称地位于激发激光相对于原子共振的失谐处。中心分量的滤波导致柯西-施瓦茨不等式的违反，在失谐为原子线宽的 60 倍时，达到 (4.8±1.0)≰1，与在相同条件下观察到的未过滤量子相关性相比，增强了四倍。
