标题： 光学驱动的铜氧化物梯子中的对称保护电子亚稳态 显示英文标题

标题： Symmetry-protected electronic metastability in an optically driven cuprate ladder

摘要： 光学激发的量子材料表现出具有显著新兴特性的非平衡态，但这些现象通常是瞬时的，在皮秒时间尺度上衰减，限制了实际应用。 推进非平衡相的设计和控制需要开发针对性策略以实现长寿命的亚稳态相。 在这里，我们报告了在模型铜氧化物梯子Sr$_{14}$Cu$_{24}$O$_{41}$中发现的对称保护电子亚稳定性。 使用飞秒共振X射线散射和光谱学，我们表明这种亚稳定性是由从链状电荷库向梯子转移空穴所驱动的。 这种超快电荷重新分布源于光学处理和激活一个在平衡状态下被对称性禁止的跳跃路径。 因此，在泵浦相干消散后，弛豫回到基态受到抑制。 我们的研究结果强调了如何通过电磁场修饰材料可以动态激活电子哈密顿量中的项，并为物质的非平衡相提供了合理的设计策略。 显示英文摘要

摘要： Optically excited quantum materials exhibit nonequilibrium states with remarkable emergent properties, but these phenomena are usually transient, decaying on picosecond timescales and limiting practical applications. Advancing the design and control of nonequilibrium phases requires the development of targeted strategies to achieve long-lived, metastable phases. Here, we report the discovery of symmetry-protected electronic metastability in the model cuprate ladder Sr$_{14}$Cu$_{24}$O$_{41}$. Using femtosecond resonant x-ray scattering and spectroscopy, we show that this metastability is driven by a transfer of holes from chain-like charge reservoirs into the ladders. This ultrafast charge redistribution arises from the optical dressing and activation of a hopping pathway that is forbidden by symmetry at equilibrium. Relaxation back to the ground state is hence suppressed after the pump coherence dissipates. Our findings highlight how dressing materials with electromagnetic fields can dynamically activate terms in the electronic Hamiltonian, and provide a rational design strategy for nonequilibrium phases of matter.