Infinite-range interactions in atomic spin systems

本项目的目标是研究具有腔介导的全对全相互作用的大自旋系统和小自旋系统。我们将进行详细的理论研究，所谓的Dicke-Ising模型，实验实施本研究单元的项目1。在这里，一个大的原子气体的集体耦合到一个腔诱导的无限程相互作用共存的伊辛型长程原子间相互作用诱导的非共振激光激发里德堡态。我们将探索这个模型中的新相和相变，并分析其创造高度相关的多体量子态的潜力。然后，我们将转向研究具有无限程交换或伊辛型相互作用的少自旋系统。该系统将在该项目中通过实验实现，使用高度激发的里德伯原子耦合到微波腔场，发挥“量子总线”的作用。附近里德伯原子之间的强偶极-偶极相互作用将允许形成最多可以容纳一个集体激发的里德伯超原子。单个的超原子将代表单个的自旋，而这些自旋又可以通过腔介导的无限程相互作用相互作用。这种具有高度可调任意范围相互作用的少体和多体量子系统的发展对于量子逻辑门的可扩展实现以及动态控制和可配置量子模拟器的实现至关重要。

The goal of the present project is the investigation of large and small spin systems with cavity mediated all-to-all interactions. We will perform detailed theoretical studies of the so-called Dicke-Ising model, experimentally implemented in Project 1 of this Research Unit. Here, the infinite-range interactions induced by the collective coupling of a large atomic gas to a cavity coexist with Ising-type long-range interatomic interactions induced by off-resonant laser excitation of Rydberg states. We will explore the novel phases and phase transitions in this model and analyze its potential to create highly correlated many-body quantum states. We will then turn to the study of a few-spin system with infinite-range exchange or Ising-type interactions. This system will be realised experimentally in this project using highly-excited Rydberg atoms coupled to a microwave cavity field that plays the role of a "quantum bus". Strong dipole-dipole interactions between the nearby Rydberg atoms will permit the formation of Rydberg superatoms that can accommodate at most one collective excitation. Individual superatoms would represent single spins, which in turn can interact with each other via the cavity-mediated infinite-range interactions. The development of such few- and many-body quantum systems with highly-tunable arbitrary-range interactions will be of paramount importance for scalable implementations of quantum logic gates and the realization of dynamically controlled and configurable quantum simulators.