观测物质波中速度层级的涌现
Observing the emergence of a velocity hierarchy in matter waves
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中文总结 AI 辅助
研究在强相互作用晶格气体中观测到物质波涌现的速度层级，结合淬火光谱与时间分辨关联测量，揭示了超流体-莫特绝缘体相变附近速度的分离规律及类相对论不变性，确立其为强关联量子动力学的涌现特征。
中文摘要 AI 辅助
色散介质中的经典波自然会表现出不同的相速度和群速度。在强多体相互作用下，物质波是否会出现类似的速度分离，这一问题尚未得到实验探索。本文中，我们在强相互作用晶格气体中观测到了速度层级的涌现。结合淬火光谱与时间分辨关联测量，我们在超流体-莫特绝缘体相变过程中独立确定了声速、群速度和相速度。这些速度在相变附近几乎简并，但随着莫特能隙打开且准粒子色散呈现类相对论的质量形式，它们会逐渐分离。值得注意的是，相相干前沿的传播速度快于利布-罗宾逊速度标度，同时仍完全符合局域性。在绝缘区，测得的速度满足类相对论不变性关系。我们的结果确立了传播速度层级作为强关联量子动力学的涌现特征。
英文摘要
Classical waves in dispersive media naturally exhibit distinct phase and group velocities. Whether an analogous separation of velocities can emerge in matter waves under strong many-body interactions has remained experimentally unexplored. Here, we demonstrate the emergence of a velocity hierarchy in a strongly interacting lattice gas. Using quench spectroscopy together with time-resolved correlation measurements, we independently determine the sound, group, and phase velocities across the superfluid-to-Mott-insulator transition. These velocities are nearly degenerate close to the transition, but progressively separate as the Mott gap opens and the quasiparticle dispersion acquires a massive relativistic-like form. Strikingly, phase-coherence fronts propagate faster than the Lieb-Robinson velocity scale while remaining fully consistent with locality. The measured velocities satisfy a relativistic-like invariance relation in the insulating regime. Our results establish propagation-velocity hierarchies as emergent signatures of strongly correlated quantum dynamics.
