SFB 1225: Isolated quantum systems and universality in extreme conditions (ISOQUANT)

在极端条件下孤立量子系统的理解需要解决悬而未决的问题，这是相关的广泛的专题应用，从粒子和核物理到原子和凝聚态物理。尽管在诸如温度、密度、场强等关键参数上存在显著差异，但许多这样的系统表现出特征性的共同性质。宇宙机制的存在，即使是看似不同的物理系统之间的定量协议也可以被观察到，这推动了跨传统专业领域的研究活动的显著趋同。我们的目标是对极端条件下孤立量子系统的普遍性进行分类和定量理解，以及深入了解特定微观系统如何偏离普遍性的问题。专注于孤立系统提供了特别干净的实验和理论设置。极端的条件会增强对微观性质的记忆的丧失，而普遍性正是起源于这些微观性质。更确切地说，我们调查的极端条件下，无量纲的相互作用强度，场的期望值和特征能量尺度的组合成为统一的顺序。除了强耦合，这也考虑到相关的弱耦合制度，在强场或大波动的存在。在第一个资助期间，我们发现了这些制度的新的普适性类，提供了令人兴奋的不同的物理系统之间的新联系，从热等离子体到冷气体。这一建议的一个重要优势涉及瞬态现象的调查，以及从一个共同的角度平衡属性。这使我们能够解决一些最紧迫的问题，涉及热化过程，强场与真空和物质的相互作用，以及极端条件下系统的相结构。在实验上，这些问题将在超相对论重离子碰撞、高电荷离子的精密光谱学和超冷量子气体的帮助下进行研究。前者探索强相互作用（QCD）和量子电动力学（QED）理论，而超冷量子气体则用于设计通用模型系统，作为复杂多体问题的量子模拟器。该研究计划的范围需要在海德堡提供理想环境的不同专业领域的共同努力。

The understanding of isolated quantum systems in extreme conditions requires the resolution of outstanding open questions, which are relevant for a wide range of topical applications from particle and nuclear physics to atomic and condensed matter physics. Many such systems exhibit characteristic common properties despite dramatic differences in key parameters such as temperature, density, field strength and others. The existence of universal regimes, where even quantitative agreements between seemingly disparate physical systems can be observed, drives a remarkable convergence of research activities across traditional lines of specialisation.Our goal is the classification and quantitative understanding of universal aspects of isolated quantum systems in extreme conditions, as well as gaining insight into the question of how particular microscopic systems deviate from universality. Focussing on isolated systems offers particularly clean experimental and theoretical settings. Extreme conditions enhance the loss of memory of microscopic properties from which universality originates. More precisely, we investigate extreme conditions where the dimensionless combination of the interaction strength, field expectation values and characteristic energy scale becomes of order unity. Apart from strong couplings, this takes into account also relevant weak-coupling regimes in the presence of strong fields or large fluctuations. During the first funding period we discovered new universality classes in these regimes, providing exciting new links between different physical systems ranging from hot plasmas to cold gases.An important strength of this proposal concerns the investigation of transient phenomena as well as equilibrium properties from a common perspective. This allows us to address some of the most pressing questions concerning the thermalisation process, the interplay of strong fields with the vacuum and matter, and the phase structure of systems in extreme conditions. Experimentally, these questions will be investigated with the help of ultrarelativistic heavy-ion collisions, precision spectroscopy with highly charged ions, and ultracold quantum gases. While the former explore the theory of the strong interaction (QCD) and quantum electrodynamics (QED), ultracold quantum gases are used to engineer generic model systems as quantum simulators for complex many-body problems. The scope of this research programme requires a concerted effort across different fields of specialisation for which Heidelberg provides an ideal environment.