集群和宏观相干性的破坏：从不对称性度量的角度
Breaking of clustering and macroscopic coherence under the lens of asymmetry measures
AI总结：
本文研究了相互作用对一维系统中自发对称破缺现象的影响，通过考虑具有守恒域墙数的相互作用模型，发现局部淬火可增强量子干涉，产生宏观磁化分布，并通过Entanglement Asymmetry和Quantum Fisher Information度量量子相干性。
摘要：
在一维系统中，自发对称破缺（SSB）状态本质上是脆弱的，因为注入高于基态的非零能量密度预计会恢复对称性。这种不稳定性意味着局部扰动可能导致宏观相关性分布、集群性质的破坏以及宏观量子叠加。本文通过考虑具有守恒域墙数的相互作用模型，该模型具有铁磁基态，破坏了哈密顿量的Z2对称性。我们首先展示局部淬火会增强量子干涉，产生直接反映模型散射相位的宏观磁化分布。然后，我们使用两个不对称性度量，即纠缠不对称性（EA）和量子 Fisher 信息（QFI），来表征与磁化波动相关的量子相干性。通过关注与扰动的光锥大小相当的子系统，我们确认了在整个扰动区域内宏观量子相干性的出现。最后，我们讨论了EA和QFI之间的联系，并展示纯态的方差/EA不等式可以推广到混合态的QFI/EA不等式。
英文摘要：
In one-dimensional systems, spontaneous symmetry breaking (SSB) states are fragile by nature, as the injection of a non-zero energy density above the ground state is expected to restore the symmetry. This instability implies that local perturbations can lead to macroscopic correlation profiles, a breaking of clustering properties and even macroscopic quantum superpositions. In this work, we investigate the effect of interaction on this phenomenology by considering an interacting model with conserved domain wall number, that possesses a ferromagnetic ground state breaking the Z2 symmetry of the Hamiltonian. We first show that a local quench in this system amplifies quantum interferences, producing a macroscopic magnetisation profile that directly reflects the scattering phase of the model. Then, we use two asymmetry measures, namely the Entanglement Asymmetry (EA) and Quantum Fisher Information (QFI), to characterise the quantum coherence associated with the fluctuations of the magnetisation. By focusing on subsystems comparable in size to the light-cone of the perturbation, we confirm the emergence of macroscopic quantum coherence throughout the whole perturbed region. Finally, we discuss the link between EA and QFI and show that the variance/EA inequality for pure state can be generalised to a QFI/EA inequality for mixed states.
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