意大利纳米技术研究所Dimitrios Trypogeorgos团队发现了光子晶体极化子凝聚体中出现的超固体。相关论文于2025年3月5日发表在《自然》杂志上。

超固体是一种违反直觉的物质相，其中其组成粒子排列成晶体结构，但它们可以自由流动而没有摩擦。这要求粒子共享一个全局宏观相，同时能够通过自发的空间自组织减少它们的总能量。50多年前，人们推测物质存在超固相。然而，直到最近才有令人信服的实验证据，主要是使用与电磁场耦合的超冷原子玻色-爱因斯坦凝聚体（BEC）。使用与高精细度腔耦合的原子、具有大磁偶极矩的原子和自旋轨道耦合的双组分系统（显示条纹相）可创建各种形式的超固体。

研究组提供了在驱动耗散、非平衡环境中实现超固相的新实验证据，该实验基于激子-极化子在连续体（BiC）中以拓扑非平凡的束缚态凝聚，具有极低的损耗，在光子晶体波导中实现。他们以千分之几的精度测量了极化态的密度调制，表明平移对称性的破坏。直接访问波函数的相位还可以测量超固体的局部相干性。研究组展示了该合成光子材料在主体声子动力学和多模激发光谱方面的潜力。

附：英文原文

Title: Emerging supersolidity in photonic-crystal polariton condensates

Author: Trypogeorgos, Dimitrios, Gianfrate, Antonio, Landini, Manuele, Nigro, Davide, Gerace, Dario, Carusotto, Iacopo, Riminucci, Fabrizio, Baldwin, Kirk W., Pfeiffer, Loren N., Martone, Giovanni I., De Giorgi, Milena, Ballarini, Dario, Sanvitto, Daniele

Issue&Volume: 2025-03-05

Abstract: A supersolid is a counter-intuitive phase of matter in which its constituent particles are arranged into a crystalline structure, yet they are free to flow without friction. This requires the particles to share a global macroscopic phase while being able to reduce their total energy by spontaneous, spatial self-organization. The existence of the supersolid phase of matter was speculated more than 50years ago1,2,3,4. However, only recently has there been convincing experimental evidence, mainly using ultracold atomic Bose–Einstein condensates (BECs) coupled to electromagnetic fields. There, various guises of the supersolid were created using atoms coupled to high-finesse cavities5,6, with large magnetic dipole moments7,8,9,10,11,12,13, and spin–orbit-coupled, two-component systems showing stripe phases14,15,16. Here we provide experimental evidence of a new implementation of the supersolid phase in a driven-dissipative, non-equilibrium context based on exciton–polaritons condensed in a topologically non-trivial, bound state in the continuum (BiC) with exceptionally low losses, realized in a photonic-crystal waveguide. We measure the density modulation of the polaritonic state indicating the breaking of translational symmetry with a precision of several parts in a thousand. Direct access to the phase of the wavefunction allows us to also measure the local coherence of the supersolid. We demonstrate the potential of our synthetic photonic material to host phonon dynamics and a multimode excitation spectrum.

DOI: 10.1038/s41586-025-08616-9

Source: https://www.nature.com/articles/s41586-025-08616-9