Controlled Immersion of Single Neutral Atomic Impurities into an Ultracold Quantum Gas of a Different Atomic Species

具有单粒子分辨率的量子系统的相干控制打开了在基本层面上揭示量子力学现象并利用它们来设计任意量子态的可能性。在这个项目中，这种控制是通过将一种原子物种的单个或几个中性原子受控地浸入另一种原子物种的量子气体中来设想的。该项目将通过物种选择性光学陷阱设计独立定位和控制两个子系统的工具；通过标准吸收和荧光成像进行独立读出；以及通过种间费什巴赫共振调节和切换相互作用强度。该系统将探索两个主要场景：首先，该项目将解决一个问题，即在保持量子气体中单个量子比特的内部状态相干性的同时，是否有可能冷却，这与量子信息的目的高度相关。其次，对于强的种间相互作用，该系统可以用准粒子方法很好地描述，其中量子气体中的原子围绕着杂质。这种极化子，类似于通常固态物理中被声子包裹的电子，具有在通常的固态系统中找不到的显著性质。该项目将在单个和多个杂质原子之间的交叉中创建和研究极化子，并研究它们的性质，例如它们的自我定位。

Coherent control of quantum systems with single-particle resolution opens the possibility to shed light on quantum mechanical phenomena on a fundamental level and exploit them for engineering arbitrary quantum states. In this project, such a control is envisioned by controlled immersion of single or few neutral atoms of one atomic species in a quantum gas of another species. The project will devise tools for independent positioning and controlling the two sub-systems by species-selective optical traps; for independent read-out by standard absorption and fluorescence imaging; and for tuning and switching the interaction strength by inter-species Feshbach resonances. Two major scenarios will be explored with this system: First the project will address the question if cooling of single qubits in a quantum gas is possible while preserving their internal state coherences, highly relevant for quantum information purposes. Second, for strong inter-species interaction, the system is well described by a quasi-particle approach, where atoms from the quantum gas surround the impurities. Such polarons, analogous to electrons dressed by phonons in usual solid state physics, have remarkable properties which cannot be found in usual solid state systems. The project will create and investigate polarons in the crossover between single and many impurity atoms and study their properties, such as their self-localization.