论文标题
纠缠不对称性作为对称破裂的探针
Entanglement asymmetry as a probe of symmetry breaking
论文作者
论文摘要
对称和对称性破坏是现代量子物理学的两个支柱。尽管如此，量化对称性被打破了多少是一个很少关注的问题。在扩展的量子系统中，此问题本质上与感兴趣的子系统结合。因此，在这项工作中，我们从多体量子系统中的纠缠理论中借用方法，以引入对称破坏的子系统，使我们配音纠缠不对称。作为一个典型的说明，我们研究了自旋链的量子淬灭中的纠缠不对称性，其中最初破裂的全局$ u（1）$对称性是动态恢复的。我们将准粒子图片适应纠缠的演变，以分析纠缠不对称的分析性。我们发现，较大的子系统是恢复的较慢，但也是违反直觉的结果，即最初损坏了对称性，更快地恢复了对称性，这是一种量子mpemba效应，这是我们在各种系统中显示的现象。
Symmetry and symmetry breaking are two pillars of modern quantum physics. Still, quantifying how much a symmetry is broken is an issue that has received little attention. In extended quantum systems, this problem is intrinsically bound to the subsystem of interest. Hence, in this work, we borrow methods from the theory of entanglement in many-body quantum systems to introduce a subsystem measure of symmetry breaking that we dub entanglement asymmetry. As a prototypical illustration, we study the entanglement asymmetry in a quantum quench of a spin chain in which an initially broken global $U(1)$ symmetry is restored dynamically. We adapt the quasiparticle picture for entanglement evolution to the analytic determination of the entanglement asymmetry. We find, expectedly, that larger is the subsystem, slower is the restoration, but also the counterintuitive result that more the symmetry is initially broken, faster it is restored, a sort of quantum Mpemba effect, a phenomenon that we show to occur in a large variety of systems.
