近日，美国德克萨斯大学奥斯汀分校J. I. A. Li团队报道了双层激子超流体到绝缘体跃迁的观测。2026年1月28日出版的《自然》杂志发表了这项成果。

与玻色-爱因斯坦凝聚相关的最显著特性之一是超流性——在这种状态下，系统呈现出零粘滞性且流动无耗散。超流相已在多种玻子系统中被观测到，涵盖从自然存在的量子流体（如液氦）到人工设计的平台（如双层激子与冷原子系统）。理论研究表明，相互作用可能驱使玻色-爱因斯坦凝聚基态进入另一种奇异相态，该相态同时具备晶体固体与超流体的特性，被称为超固态。然而，纯粹由相互作用驱动（而非依赖外禀晶格势场）且能承载理论预言的玻色-爱因斯坦凝聚固态的材料体系，至今尚未被发现。

研究组报道了在双层磁激子的层间不平衡区域中观测到的超流-绝缘体相变。通过绘制双层凝聚体的输运行为随密度与温度的变化关系图，研究组表明绝缘相是一种由偶极相互作用稳定的稀薄激子有序态。该绝缘体在温度升高时会熔化并恢复为超流体，这一现象可能表明低温固体相同样是一种量子相干相。

附：英文原文

Title: Observation of a superfluid-to-insulator transition of bilayer excitons

Author: Zeng, Yihang, Sun, Dihao, Zhang, Naiyuan J., Nguyen, Ron Q., Shi, Qianhui, Okounkova, A., Watanabe, K., Taniguchi, T., Hone, J., Dean, C. R., Li, J. I. A.

Issue&Volume: 2026-01-28

Abstract: One of the most remarkable properties associated with Bose–Einstein condensation (BEC) is superfluidity, in which the system exhibits zero viscosity and flows without dissipation. The superfluid phase has been observed in wide-ranging bosonic systems spanning naturally occurring quantum fluids, such as liquid helium, to engineered platforms such as bilayer excitons and cold atom systems1,2,3,4. Theoretical works have proposed that interactions could drive the BEC ground state into another exotic phase that simultaneously exhibits properties of both a crystalline solid and a superfluid—termed a supersolid5,6,7,8. Identifying a material system, however, that hosts the predicted BEC solid phase, driven purely by interactions and without imposing an external lattice potential, has remained unknown9,10,11. Here we report observation of a superfluid-to-insulator transition in the layer-imbalanced regime of bilayer magnetoexcitons. Mapping the transport behaviour of the bilayer condensate as a function of density and temperature suggests that the insulating phase is an ordered state of dilute excitons, stabilized by dipole interactions. The insulator melts into a recovered superfluid on increasing the temperature, which could indicate that the low-temperature solid is also a quantum coherent phase.

DOI: 10.1038/s41586-025-09986-w

Source: https://www.nature.com/articles/s41586-025-09986-w