Studies of Lattice-Based Atomic Quantum Systems with Engineered Dissipation

这个项目的目标是理解和控制耦合到环境的小量子系统的阻尼。量子力学是可逆的，也就是说，一个量子系统的假想电影无论向前播放还是向后播放，看起来都是一样的。那么阻尼这种不可逆的东西是如何在量子物理学中出现的呢？这个项目旨在设计一个简单的模型系统，由一个“原子量子点”（一个人造原子）与一个真空（所有环境中最简单的）耦合组成。这个可调谐的实验系统，发射物质波而不是光辐射，将允许精确研究环境结构变化时的阻尼。使用大量规则间隔的原子量子点来构建类似激光的光源应该是可能的，并且利用与环境的耦合来实现一种新型的量子隧穿，这可能会在固态现象的量子模拟中得到应用。虽然第一组实验揭示了量子力学阻尼的本质，但第二组实验将研究是否可以避免由大环境引起的这种阻尼。这里，所考虑的模型系统将由一个原子组成，该原子以管状几何形状穿过一维原子气体。碰撞应该会减慢原子的速度，并完全抑制它的运动，但也许有可能利用量子力学，通过使环境有效透明来屏蔽原子的运动，这样阻尼就被抑制了。开发控制阻尼和耗散的方法对于量子模拟和量子信息科学至关重要，本项目的结果将与解决一些基本挑战相关。本项目致力于超冷原子物理背景下新型耗散系统的实验研究，重点研究工程原子量子点和可移动杂质耦合到具有可控多体特性的玻色子环境。这种系统的实现是通过使用超冷的同核原子混合物，这些混合物具有超精细状态成分，这些成分由状态相关的光势独立控制。该项目的目标包括探索自发和超辐射的物质波发射，由相干修饰引起的倏逝物质波场引起的耦合，以及超流体环境中声子激发提供的耦合，并有望实现耗散量子伊辛链。利用与一维玻色气体的耦合，该项目进一步旨在研究接近可积性的无约束杂质的耗散和相干输运，并有望观察到新的多体效应。

The goal of this project is to understand and control the damping of small quantum systems coupled to an environment. Quantum mechanics is reversible, that is, a hypothetical movie of a quantum system looks the same if it is played forward or in reverse. So how can damping, something non-reversible, emerge in quantum physics? This project aims to engineer a simple model system consisting of an "atomic quantum dot" (an artificial atom) coupled to an empty vacuum, the simplest of all environments. This tunable experimental system, which emits matter waves rather than optical radiation, will allow for precise investigation of damping as the structure of the environment is changed. It should be possible to build laser-like sources using a large number of regularly spaced atomic quantum dots, and to exploit the coupling to the environment for a novel form of quantum tunneling, which may find use in quantum simulation of solid-state phenomena. While this first set of experiments sheds light on the nature of quantum mechanical damping, a second set of experiments will investigate whether such damping due to a large environment can be avoided. Here, the model system considered will consist of an atom moving through a one-dimensional atomic gas in a tube-like geometry. Collisions should slow down the atom and damp its motion completely, but it may be possible to harness quantum mechanics to shield the atomic motion by rendering the environment effectively transparent, such that damping is suppressed. Developing ways to control damping and dissipation are of paramount importance for quantum simulation and quantum information science, and the results of this project will be of relevance in addressing some of the fundamental challenges.The project is devoted to the experimental study of novel dissipative systems in the context of ultracold atomic physics, focusing on engineered atomic quantum dots and mobile impurities coupled to a bosonic environment with controllable many-body character. The implementation of such systems is made possible through the use of ultracold, homonuclear atomic mixtures with hyperfine-state components that are independently controlled with state-dependent optical potentials. The project goals include an exploration of spontaneous and superradiant matter-wave emission, of couplings induced by evanescent matter-wave fields arising from coherent dressing, as well as couplings provided by phononic excitations of a superfluid environment, with the prospect of realizing a dissipative quantum Ising chain. Exploiting the coupling to one-dimensional Bose gases, the project furthermore aims to investigate dissipative and coherent transport for unconfined impurities near integrability, with the prospect of observing novel many-body effects.