Department of Physics, Harvard University, Cambridge, MA, USA.
ITAMP, Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, USA.
Nature. 2019 Apr;568(7751):207-211. doi: 10.1038/s41586-019-1070-1. Epub 2019 Apr 1.
Quantum phase transitions (QPTs) involve transformations between different states of matter that are driven by quantum fluctuations. These fluctuations play a dominant part in the quantum critical region surrounding the transition point, where the dynamics is governed by the universal properties associated with the QPT. Although time-dependent phenomena associated with classical, thermally driven phase transitions have been extensively studied in systems ranging from the early Universe to Bose-Einstein condensates, understanding critical real-time dynamics in isolated, non-equilibrium quantum systems remains a challenge. Here we use a Rydberg atom quantum simulator with programmable interactions to study the quantum critical dynamics associated with several distinct QPTs. By studying the growth of spatial correlations when crossing the QPT, we experimentally verify the quantum Kibble-Zurek mechanism (QKZM) for an Ising-type QPT, explore scaling universality and observe corrections beyond QKZM predictions. This approach is subsequently used to measure the critical exponents associated with chiral clock models, providing new insights into exotic systems that were not previously understood and opening the door to precision studies of critical phenomena, simulations of lattice gauge theories and applications to quantum optimization.
量子相变（QPT）涉及由量子涨落驱动的物质不同状态之间的转变。这些涨落在相变点周围的量子临界区域中起着主导作用，在这个区域中，动力学由与 QPT 相关的普遍特性所支配。尽管与经典、热驱动相变相关的时变现象在从早期宇宙到玻色-爱因斯坦凝聚态的系统中得到了广泛研究，但理解孤立、非平衡量子系统中的关键实时动力学仍然是一个挑战。在这里，我们使用具有可编程相互作用的里德堡原子量子模拟器来研究与几个不同 QPT 相关的量子临界动力学。通过研究跨越 QPT 时空间相关性的增长，我们实验验证了伊辛型 QPT 的量子 Kibble-Zurek 机制（QKZM），探索了标度普遍性并观察到超出 QKZM 预测的修正。随后，该方法用于测量手性时钟模型相关的临界指数，为以前不被理解的奇异系统提供了新的见解，并为临界现象的精密研究、格点规范理论的模拟以及量子优化的应用开辟了道路。
