From bipartite to many-particle entanglement of ultracold atoms

在这个项目中，我们将探索使用玻色-爱因斯坦凝聚体中的自旋动力学来创建纠缠原子态。我们将实施一种原子零差技术，以研究单粒子水平上所产生的状态的惊人的非经典特性，从而获得对基本微观过程的重要见解。我们将研究从纠缠原子对到大纠缠原子团的纠缠态的产生，通过原子零差测量揭示连续变量纠缠，并改进得到高程度的Einstein-Podolsky-罗森（EPR）纠缠。所创建的状态的纠缠将通过单粒子精度的量子态的层析重建来证明。我们将通过耦合纠缠粒子来观察原子对干涉中的HOM效应。 无论是EPR纠缠和HOM效应将研究越来越多的粒子和方法的表征所产生的介观状态将被开发。最后，我们将研究自旋动力学和微波耦合相结合的薛定谔小猫态的产生。总之，该项目为探索从少粒子纠缠到多粒子纠缠的转变提供了一条新的途径，具有探索宏观量子系统经典性开始的令人兴奋的视角。

Within this project, we will explore the creation of entangled atomic states using spin dynamics in Bose-Einstein condensates. We will implement an atomic homodyning technique to investigate the striking non-classical properties of the created states on the single-particle level and thereby gain important insights on the fundamental microscopic processes. We will investigate the creation of entangled states from entangled atom pairs to large clusters of entangled atoms.Continuous variable entanglement will be revealed by atomic homodyne measurements and improved to obtain a high degree of Einstein-Podolsky-Rosen (EPR) entanglement. The entanglement of the created states will be demonstrated by a tomographic reconstruction of the quantum state with single-particle precision. We will observe the Hong-Ou-Mandel (HOM) effect in the interference of atom pairs by coupling the entangled particles. Both the EPR entanglement and the HOM effect will be studied for an increasing number of particles and methods for the characterization of the resulting mesoscopic states will be developed. Finally, the creation of Schrödinger kitten states by a combination of spin dynamics and microwave coupling will be investigated.In summary, the project provides a new path to explore the transition from few- to many-particle entanglement with the exciting perspective to probe the onset of classicality in macroscopic quantum systems.