The nature of hadrons is one of the most fundamental mysteries of physics. It is generally agreed that they are made of “colored” quarks, which move nearly free at short scales but are confined inside hadrons by strong interactions at large distances. Because of confinement, quarks are never directly observable and, experimentally, their properties can be tested only indirectly, via high energy collisions. Here we show that superinsulating films realize a complete, one-color model system of hadron physics with Cooper pairs playing the role of quarks. We report measurements on highly controlled NbTiN films that provide a window into the interior of "Cooper pair mesons" and present the first direct evidence of asymptotic freedom, ‘t Hooft’s dual superconductivity confinement mechanism, and magnetic monopoles.

强子的性质是物理学中最基本的奥秘之一。人们普遍同意，它们是由“彩色”夸克制成的，它们在短尺度上几乎可以自由移动，但由于强距离的强相互作用而被限制在强子内部。由于局限性，夸克永远无法直接观察到，从实验上讲，只能通过高能碰撞间接地测试夸克的性质。在这里，我们证明了超级绝缘膜通过库珀对起到夸克的作用，实现了一个完整的，单色的强子物理模型系统。我们报告了对高度受控的NbTiN薄膜的测量，这些薄膜提供了进入“库珀对介子”内部的窗口，并提供了渐近自由度，'t Hooft双重超导约束机制和磁单极子的第一个直接证据。