AI 中文总结
本文在光学环形腔中追踪自组织原子晶体的戈德斯通模随机输运，发现扩散常数随$1/N$减小，归一化后呈普适曲线，拓展了连续对称性破缺的研究范畴。
AI 中文摘要
连续对称性的自发破缺会产生无质量的戈德斯通模，其可在零能量成本下跨越简并流形演化。戈德斯通模主要通过激发谱、模软化或集体振荡被识别，然而其在本征涨落与耗散下的时域输运却仍未得到充分探索。本文中，我们直接追踪了光学环形腔内自组织原子晶体中戈德斯通模的随机输运。该环形腔将序参量相位映射到涌现晶体的实空间位置。无任何外部微扰时，基本光子散射反冲驱动集体输运，而腔耗散产生摩擦。我们通过测量腔输出相位，监测原子及其自生成光学晶格的单个轨迹。我们发现扩散常数随$1/N$减小，表明所有原子作为刚性整体而非独立个体运动。通过调节朗之万驱动力和腔介导的阻尼，我们证明归一化扩散常数可坍缩为单一普适曲线。本工作将连续对称性破缺的研究从激发频率测量拓展至输运的实时追踪，为研究受驱耗散量子物质中的非平衡集体输运、声子动力学及缺陷形成开辟了途径。
英文摘要
Spontaneous breaking of a continuous symmetry produces a massless Goldstone mode that can evolve across a degenerate manifold at zero energy cost. Goldstone modes have been identified primarily through excitation spectra, mode softening or collective oscillations. However, their time-domain transport under intrinsic fluctuations and dissipation has remained largely unexplored. Here we directly track the stochastic transport of a Goldstone mode in a self-organized atomic crystal inside an optical ring cavity. The ring cavity maps the order-parameter phase onto the real-space position of the emergent crystal. Without any external perturbation, fundamental photon-scattering recoil drives the collective transport, while cavity dissipation generates friction. We monitor individual trajectories of the atoms and their self-generated optical lattice by measuring the cavity output phase. We find that the diffusion constant decreases as $1/N$, indicating that all atoms move collectively as a rigid object rather than independently. By tuning the Langevin driving force and cavity-mediated damping, we show that the normalized diffusion constant collapses onto a single universal curve. This work extends the study of continuous symmetry breaking from excitation-frequency measurements to real-time tracking of transport, and opens routes for studying non-equilibrium collective transport, phonon dynamics, and defect formation in driven-dissipative quantum matter.
