The general theory of dark solitons relies on repulsive interactions and, therefore, predicts the impossibility to form dark-soliton bound states. One important exception to this prediction is the observation of bound solitons in nonlocal nonlinear media. Here, we report that exciton-polariton superfluids can also sustain dark-soliton molecules, although the interactions are fully local. With a novel all-optical technique, we create two dark solitons that bind together to form an unconventional dark-soliton molecule. We demonstrate that the stability of this structure and the separation distance between two dark solitons is tightly connected to the driven-dissipative nature of the polariton fluid.

中文翻译：

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激子-极化子超流体中的暗孤子分子

暗孤子的一般理论依赖于排斥相互作用，因此可以预测不可能形成暗孤子束缚态。这一预测的一个重要例外是在非局域非线性介质中观察束缚孤子。在这里，我们报告激子-极化子超流体也可以维持暗孤子分子，尽管相互作用是完全局部的。利用一种新颖的全光学技术，我们创建了两个暗孤子，它们结合在一起形成一个非常规的暗孤子分子。我们证明了这种结构的稳定性以及两个暗孤子之间的分隔距离与极化子流体的驱动耗散特性紧密相关。