Spectroscopy is a crucial laboratory technique for understanding quantum systems through their interactions with the electromagnetic radiation. Particularly, spectroscopy is capable of revealing the physical structure of molecules, leading to the development of the maser—the forerunner of the laser. However, real-world applications of molecular spectroscopy are mostly confined to equilibrium states, due to computational and technological constraints; a potential breakthrough can be achieved by utilizing the emerging technology of quantum simulation. Here we experimentally demonstrate through a toy model, a superconducting quantum simulator capable of generating molecular spectra for both equilibrium and non-equilibrium states, reliably producing the vibronic structure of diatomic molecules. Furthermore, our quantum simulator is applicable not only to molecules with a wide range of electronic-vibronic coupling strength, characterized by the Huang-Rhys parameter, but also to molecular spectra not readily accessible under normal laboratory conditions. These results point to a new direction for predicting and understanding molecular spectroscopy, exploiting the power of quantum simulation.

光谱学是通过量子系统与电磁辐射的相互作用来理解量子系统的一项重要实验室技术。特别是，光谱学能够揭示分子的物理结构，从而促成了激光的前身——脉泽激光器的发展。然而，由于计算和技术限制，分子光谱的实际应用大多局限于平衡状态；利用新兴的量子模拟技术可以实现潜在的突破。在这里，我们通过玩具模型实验性地展示了一种超导量子模拟器，能够为平衡和非平衡状态生成分子光谱，可靠地生成双原子分子的电子振动结构。此外，我们的量子模拟器不仅适用于具有广泛的电子-振动耦合强度的分子，以 Huang-Rhys 参数为特征，而且适用于在正常实验室条件下不易获得的分子光谱。这些结果指出了利用量子模拟的力量预测和理解分子光谱的新方向。