We investigate two-color photon correlations in the light emitted by two strongly driven, strongly interacting two-level emitters. The correlations are interpreted introducing the collective dressed states picture, which allows us to describe both bunching and antibunching based on the allowed and prohibited transitions. At odds from weakly interacting emitters, the strong interaction lifts the degeneracy of the energy differences between the different states, leading to a temporal breaking of symmetry for the correlations: photons of different frequencies may not be emitted in any order. Finally, we show that most of the virtual processes, which involve pairs of photons, yield nonclassical correlations when the sum of their energies fits any of the interaction-induced sidebands in the emitted spectrum. In particular, depending on the frequency of the emitted photons, correlations strong enough to violate Bell inequalities can appear.

中文翻译：

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一对强耦合两能级发射器的光子-光子相关性

我们研究了由两个强烈驱动，相互作用的两能级发射器发出的光中的两种颜色的光子相关性。解释了相关性，引入了集体穿戴状态图，这使我们能够基于允许和禁止的转换来描述聚束和反聚束。与弱相互作用的发射体相矛盾的是，强相互作用解除了不同状态之间能量差的简并性，导致相关性的时间对称性破裂：不同频率的光子可能不会以任何顺序发射。最后，我们表明，涉及光子对的大多数虚拟过程，当它们的能量之和适合发射光谱中任何由相互作用引起的边带时，就会产生非经典的相关性。特别是，