近日，瑞士苏黎世联邦理工学院Jérôme Faist团队研究了分数和整数量子霍尔相的可调真空场控制。相关论文于2025年5月14日发表在《自然》杂志上。

在量子力学中，空的空间不是空的，而是以真空场波动为特征的，这是兰姆位移、自发辐射和卡西米尔效应等现象的基础。由于它们在自由空间原子物理学中的相对贡献较小，传统上在固态系统中被忽视了。然而，最近，低维系统中电子关联和量子电动力学效应之间的相互作用已成为凝聚态物理学中一个快速发展的领域，对量子材料和器件工程具有重大意义。量子霍尔体系中的高迁移率二维电子气为研究真空电磁场如何影响强关联电子态提供了一个理想的平台。   

研究组证明，调整二维电子气和悬停分裂环谐振器的真空场之间的耦合强度，可以显著降低奇数整数填充因子下的交换分裂，同时增强填充因子4/3、5/3和7/5下的分数量子霍尔间隙。

理论分析表明，这些效应源于在强真空电场梯度区域中由虚腔光子介导的有效长程吸引相互作用。该发现揭示了一种新的机制，通过这种机制，腔真空场可以重塑量子霍尔系统中的电子关联，建立了一种操纵低维材料中相关量子相的新方法，并为在紧凑型器件中设计量身定制的多体相互作用铺平了道路。

附：英文原文

Title: Tunable vacuum-field control of fractional and integer quantum Hall phases

Author: Enkner, Josefine, Graziotto, Lorenzo, Borii, Dalin, Appugliese, Felice, Reichl, Christian, Scalari, Giacomo, Regnault, Nicolas, Wegscheider, Werner, Ciuti, Cristiano, Faist, Jrme

Issue&Volume: 2025-05-14

Abstract: In quantum mechanics, empty space is not void but is characterized by vacuum-field fluctuations, which underlie phenomena such as the Lamb shift1, spontaneous emission, and the Casimir effect2. Due to their quantitatively small relative contributions in free-space atomic physics, they were traditionally overlooked in solid-state systems. Recently, however, the interplay between electronic correlations and quantum electrodynamical effects in low-dimensional systems has become a rapidly advancing area in condensed matter physics3,4,5, with substantial implications for quantum materials and device engineering. High-mobility two-dimensional electron gases in the quantum Hall regime6 offer an ideal platform to investigate how vacuum electromagnetic fields affect strongly correlated electronic states. Here we demonstrate that adjusting the coupling strength between a two-dimensional electron gas and the vacuum fields of a hovering split-ring resonator leads to a significant reduction in exchange splitting at odd-integer filling factors, along with an enhancement of fractional quantum Hall gaps at filling factors 4/3, 5/3 and 7/5. Theoretical analysis indicates that these effects stem from an effective long-range attractive interaction mediated by virtual cavity photons in regions with strong vacuum electric field gradients. Our findings uncover a new mechanism by which cavity vacuum fields can reshape electronic correlations in quantum Hall systems, establishing a new approach for manipulating correlated quantum phases in low-dimensional materials and paving the way for engineering tailored many-body interactions in compact devices.

DOI: 10.1038/s41586-025-08894-3

Source: https://www.nature.com/articles/s41586-025-08894-3