Quantum simulation of spin models with tunable atom arrays

该项目旨在实现一个使用冷原子的量子自旋模型模拟器。该协议包括激光冷却Rb原子，并与单个原子并行加载多个光学微陷阱。原子的荧光成像允许检测空陷阱，并通过熄灭这些陷阱来消除缺陷。然后，填充的陷阱被重新排列，以产生没有缺陷的规则原子阵列。该协议提供了实验的高度重复性，可以以每秒高达10次实验的高重复率进行。自旋自由度编码在每个原子最外层电子的内能态中，例如电子的超精细状态，量子自旋模型依赖于不同自旋之间的相互作用。由于远在基态的Rb原子之间不存在长程相互作用，需要通过将原子最外层的电子提升到高激发里德堡能级来引入这些相互作用。这使得能够在几微米的远距离上实现强大的范德瓦尔斯相互作用。多体系统中的里德堡激发可以观察集体动力学、纠缠和实现量子信息协议，以及设计模拟自旋模型所需的多体相互作用。另一个长期目标是将原子阵列与光子晶体波导腔接口，其中原子以腔模式与光子强烈耦合。通过腔模式耦合的原子量子比特阵列的确定性制备使得发展健壮和可扩展的量子网络成为可能。

This project aims at realising a simulator for quantum spin models using cold atoms. The protocol involves laser cooling of rubidium atoms and loading of many optical microtraps in parallel with single atoms. Fluorescence imaging of the atoms allows for detecting empty traps and removing defects by extinguishing these traps. The populated traps are then rearranged to produce a regular array of atoms without defects. This protocol provides a high degree of reproducibility of the experiments and can be performed with high repetition rates of up to 10 experimental runs per second.The atoms localised in the traps serve as individual spins. The spin degree of freedom is encoded in the internal energy state of the outermost electron of each atom, e.g. the hyperfine state of the electron.Quantum spin models rely on the interaction between different spins. As no long-range interactions exist between distant rubidium atoms in their ground state, these interactions need to be introduced by promoting the outermost electron of the atoms to highly excited Rydberg levels. This enables strong van-der-Waals interactions over long distances of several microns. Rydberg excitations in many-body systems allow for observing collective dynamics, entanglement and realising quantum information protocols, as well as engineering the many-body interactions necessary for simulating spin models.Another long term goal is to interface the atom arrays with photonic crystal waveguide cavities, where the atoms are strongly coupled to the photons in the cavity mode. The deterministic preparation of atomic qubit arrays coupled via cavity modes allows for developing robust and scalable quantum networks.