AC-driven Quantum Phase Transitions

量子相变是多体系统在零温度下发生的状态的剧烈变化。 对非平衡条件下的这种临界行为知之甚少，在本项目中，这种临界行为将由周期性场（“交流驱动”）产生。我们的主要目标是-理论上制定，分析和解释AC驱动的量子相变。- 研究在静态系统中没有类似物的非绝热单色驱动作用下物质的新状态的存在。应用已建立的分析和数值方法，以描述AC驱动的关键行为，到目前为止尚未探索的模型。- 探索使用新的理论方法，如有效配分函数和几何相（Berry相），以分析非平衡条件下的临界现象。讨论最近的国家的最先进的实验，如玻色-爱因斯坦凝聚在光学腔的结果的相关性。

A quantum phase transition is a drastic change of state of a many-body system which occurs at zero temperature. Relatively little is known about such critical behaviour under nonequilibrium conditions, which in this project will be generated by periodic fields (`AC-driving'). Our key objectives are- to theoretically formulate, analyse, and interpret AC-driven quantum phase transitions. - to investigate the existence of novel states of matter under the effect of a nonadiabatic monochromatic driving with no analogues in static systems.- to apply established analytical and numerical methods in order to describe AC-driven critical behavior for so far unexplored models. - to explore the use of new theoretical methods, such as an effective partition function and the geometrical phase (Berry phase), in order to analyse critical phenomena under nonequilibrium conditions.- to discuss the relevance of the results for recent state-of-the-art experiments such as Bose-Einstein condensates in optical cavities.