Quantum phase transitions play an important role in shaping the phase diagram of high-temperature cuprate superconductors. These cuprates possess intertwined orders which interact strongly with superconductivity. However, the evidence for the quantum critical point associated with the charge order in the superconducting phase remains elusive. Here, we reveal the short-range charge orders and the spectral signature of the quantum fluctuations in ${\mathrm{La}}_{2-x}{\mathrm{Sr}}_x{\mathrm{CuO}}_4$ (LSCO) near the optimal doping using high-resolution resonant inelastic x-ray scattering. On performing calculations through a diagrammatic framework, we discover that the charge correlations significantly soften several branches of phonons. These results elucidate the role of charge order in the LSCO compound, providing evidence for quantum critical scaling and discommensurations associated with charge order.

中文翻译：

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电荷序的量子波动导致超导铜酸盐中的声子软化

量子相变在塑造高温铜酸盐超导体的相图方面起着重要作用。这些铜酸盐具有与超导性强烈相互作用的交织有序。然而，与超导阶段电荷顺序相关的量子临界点的证据仍然难以捉摸。在这里，我们揭示了短程电荷顺序和量子涨落的光谱特征${拉}_{2-X}{锶}_X{\mathrm{氧化铜}}_4$(LSCO) 接近最佳掺杂使用高分辨率共振非弹性 X 射线散射。在通过图解框架进行计算时，我们发现电荷相关性显着软化了声子的几个分支。这些结果阐明了 LSCO 化合物中电荷顺序的作用，为与电荷顺序相关的量子临界缩放和不协调提供了证据。