Periodically-driven quantum systems are currently explored in view of realizing novel many-body phases of matter. This approach is particularly promising in gases of ultracold atoms, where sophisticated shaking protocols can be realized and inter-particle interactions are well controlled. The combination of interactions and time-periodic driving, however, often leads to uncontrollable heating and instabilities, potentially preventing practical applications of Floquet-engineering in large many-body quantum systems. In this work, we experimentally identify the existence of parametric instabilities in weakly-interacting Bose-Einstein condensates in strongly-driven optical lattices through momentum-resolved measurements. Parametric instabilities can trigger the destruction of weakly-interacting Bose-Einstein condensates through the rapid growth of collective excitations, in particular in systems with weak harmonic confinement transverse to the lattice axis.

中文翻译：

---

周期性驱动的一维光学晶格中相互作用玻色子的参数不稳定性

考虑到实现物质的新颖多体相，目前正在探索周期性驱动的量子系统。这种方法在超冷原子气体中特别有前途，在这种气体中，可以实现复杂的振荡方案，并且可以很好地控制粒子间的相互作用。但是，相互作用和时间周期驱动的结合常常导致无法控制的加热和不稳定性，从而有可能阻止Floquet工程在大型多体量子系统中的实际应用。在这项工作中，我们通过动量分辨测量实验性地确定了强驱动光学晶格中弱相互作用的玻色-爱因斯坦凝聚物中参数不稳定性的存在。