Non-signalling boxes (NS) are theoretical resources defined by the principle of no-faster-than-light communication. They generalize quantum correlations, and some of them are known to collapse communication complexity (CC). However, this collapse is strongly believed to be unachievable in Nature, so its study provides intuition on which theories are unrealistic. In the present letter, we find a better sufficient condition for a nonlocal box to collapse CC, thus extending the known collapsing region. In some slices of NS, we show this condition coincides with an area outside of an ellipse.

翻译：非信号盒子（NS）是由不可超光速通信原理定义的理论资源。它们推广了量子关联，并且已知其中一些盒子能够坍缩通信复杂性（CC）。然而，这种坍缩被普遍认为在自然界中无法实现，因此对其研究有助于理解哪些理论是不切实际的。在本快报中，我们找到了非局域盒子坍缩CC的更优充分条件，从而扩展了已知的坍缩区域。在NS的某些切片中，我们证明该条件与椭圆外部的区域重合。