An exceptional point (EP) arises when both the eigenvectors and eigenvalues coalesce, which in a physical system can be achieved by engineering the gain and loss coefficients, leading to a wide variety of counterintuitive phenomena. In photonic systems, the loss and gain are generally realized by the special design of the samples. Light–matter hybrid exciton polaritons, however, are inherent non-Hermitian systems in which EPs can be approached easier such as in virtue of nonlinearity. In this work we demonstrate the existence of an EP in an exciton polariton condensate in a double-well potential. Near the EP, the polariton condensate localized in one potential well can be switched off by an additional optical excitation in the other well with very low (far below threshold) power, which surprisingly induces additional loss into the system. Increasing the power of the additional laser leads to a situation in which gain dominates in both wells again, such that the polaritons recondense in the two potential wells. The switching off near the EP can also be realized by the polariton nonlinearity induced blueshift in the same structure. Our results offer a simple way to optically manipulate the polariton condensation process in a double-well potential. Extending such a configuration to complex potential well lattices offers exciting prospects to explore high-order EPs and non-Hermitian topological photonics in a nonequilibrium many-body system.

中文翻译：

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关闭异常点附近的微腔极化子冷凝物

当特征向量和特征值合并时会出现一个异常点（EP），这在物理系统中可以通过设计增益和损失系数来实现，从而导致各种违反直觉的现象。在光子系统中，损耗和增益一般通过样品的特殊设计来实现。然而，光物质混合激子极化子是固有的非厄米系统，其中 EP 可以更容易地接近，例如凭借非线性。在这项工作中，我们证明了在双阱势的激子极化子凝聚物中存在 EP。在 EP 附近，定位在一个势阱中的极化子凝聚物可以通过在另一个势阱中以非常低（远低于阈值）功率的额外光学激发来关闭，这令人惊讶地导致系统中的额外损耗。增加附加激光器的功率会导致增益在两个阱中再次占主导地位，从而极化子在两个势阱中重新凝聚。EP附近的关断也可以通过相同结构中的极化子非线性引起的蓝移来实现。我们的结果提供了一种简单的方法来光学操纵双阱电位中的极化子凝聚过程。将这种配置扩展到复杂的势阱晶格，为探索非平衡多体系统中的高阶 EP 和非厄米拓扑光子学提供了令人兴奋的前景。EP附近的关断也可以通过相同结构中的极化子非线性引起的蓝移来实现。我们的结果提供了一种简单的方法来光学操纵双阱电位中的极化子凝聚过程。将这种配置扩展到复杂的势阱晶格，为探索非平衡多体系统中的高阶 EP 和非厄米拓扑光子学提供了令人兴奋的前景。EP附近的关断也可以通过相同结构中的极化子非线性引起的蓝移来实现。我们的结果提供了一种简单的方法来光学操纵双阱电位中的极化子凝聚过程。将这种配置扩展到复杂的势阱晶格，为探索非平衡多体系统中的高阶 EP 和非厄米拓扑光子学提供了令人兴奋的前景。