Observation of microscopic confinement dynamics by a tunable topological $θ$-angle

作者：Wei-Yong Zhang, Ying Liu, Yanting Cheng, Ming-Gen He, Han-Yi Wang, Tianyi Wang, Zihang Zhu, Guo-Xian Su, Zhaoyu Zhou, Yong-Guang Zheng, Hui Sun, Bing Yang, Philipp Hauke, Zheng Wei, Jad C. Halimeh, Zhen-Sheng Yuan, Jian-Wei Pan · 发表于：arXiv (Cornell University) · 年份：2023 · DOI：10.48550/arxiv.2306.11794 · 被引用次数：9 · 研究领域：Quantum Information and Cryptography、Quantum Computing Algorithms and Architecture、Quantum and electron transport phenomena

The topological $θ$-angle is central to the understanding of a plethora of phenomena in condensed matter and high-energy physics such as the strong CP problem, dynamical quantum topological phase transitions, and the confinement--deconfinement transition. Difficulties arise when probing the effects of the topological $θ$-angle using classical methods, in particular through the appearance of a sign problem in numerical simulations. Quantum simulators offer a powerful alternate venue for realizing the $θ$-angle, which has hitherto remained an outstanding challenge due to the difficulty of introducing a dynamical electric field in the experiment. Here, we report on the experimental realization of a tunable topological $θ$-angle in a Bose--Hubbard gauge-theory quantum simulator, implemented through a tilted superlattice potential that induces an effective background electric field. We demonstrate the rich physics due to this angle by the direct observation of the confinement--deconfinement transition of $(1+1)$-dimensional quantum electrodynamics. Using an atomic-precision quantum gas microscope, we distinguish between the confined and deconfined phases by monitoring the real-time evolution of particle--antiparticle pairs, which exhibit constrained (ballistic) propagation for a finite (vanishing) deviation of the $θ$-angle from $π$. Our work provides a major step forward in the realization of topological terms on modern quantum simulators, and the exploration of rich physics they...