Quantum dynamics of low-dimensional atomic Fermi gases

自世纪前发现超导性以来，相关量子多体系统已经从科学特性发展成为传感器或医疗仪器等商业设备的关键组件。然而，认识和理解强相关物质的集体状态仍然是重大的科学挑战。在未解决的难题中，低维费米量子系统起着关键作用，因为许多有趣的效应，如铜氧化物中的高Tc超导性，量子霍尔效应和Luttinger液体行为都与降维密切相关。目前特别感兴趣的是这些多体系统的非平衡动力学。对远离平衡态的涌现态的理解构成了物理学中的重大挑战之一，并且对于应用非常重要，例如在下一代量子设备和量子计算中的能量或信息传输。需要克服的一个主要困难是，固态动力学实验经常被与环境的强耦合所淹没，由此产生的退相干破坏了已经在短时间尺度上的真正量子动力学。近年来，利用超冷原子量子气体自下而上组装强关联量子多体系统已成为可能。这种新颖的方法创造了最纯净和最广泛的可调谐“材料”，可以在其中研究量子多体物理学。它们被认为是理想的候选人，既可以解开观察到的，但尚未理解的，固态效应的奥秘，也可以实现全新的量子相，非常符合费曼的“量子模拟器”概念。也许最重要的是，冷原子气体为非平衡演化提供了一个理想的试验场，因为与系统的典型能量/时间尺度相比，温度变化非常快，并且由于它们与环境的弱耦合，动力学在很长一段时间内保持一致。

Since the discovery of superconductivity a century ago, correlated quantum many-body systems have evolved from a scientific peculiarity to key components of commercially available devices such as sensors or medical instrumentation. Yet, both realizing and understanding collective states of strongly correlated matter remain major scientific challenges. Among the unresolved puzzles, low-dimensional fermionic quantum systems play a pivotal role, because a number of intriguing effects such as high-Tc superconductivity in the cuprates, the quantum Hall effect, and Luttinger liquid behaviour are intimately linked to reduced dimensionality. Of particular current interest is the non-equilibrium dynamics of these many-body systems. The understanding of emergent states far from equilibrium constitutes one of the grand challenges in Physics and is of great importance for applications, e.g. for the transport of energy or information in the next generation of quantum devices and in quantum computing. A major difficulty to be overcome is that dynamical experiments in the solid state often are overwhelmed by the strong coupling to the environment and the resulting decoherence destroys the genuine quantum dynamics already on short time scales. In recent years, it has become possible to assemble strongly correlated quantum many-body systems in a bottom-up approach using ultracold atomic quantum gases. This novel approach has created the purest and most widely tunable "materials", in which quantum many-body physics can be studied. They are considered ideal candidates for both unravelling the mysteries of observed, but not yet understood, effects in the solid state and for realizing completely new quantum phases, very much in the sense of Feynman's concept of a "quantum simulator". Perhaps most importantly, cold atomic gases provide an ideal testing ground for non-equilibrium evolution because the tuneability is very rapid compared to the typical energy/time scales of the system and the dynamics remains coherent for long times by virtue of their weak coupling to the environment.