题 目：The study of quantum Hall interfaces
Edge (surface) states of quantum Hall (QH) and other topological states of matter provide a window to peek into the bulk topological properties of the system via the principle of bulk/edge correspondence. More generally, an edge can be viewed as a special case of an interface between two different phases of matter, namely one of the two phases is a vacuum. A quantum Hall (QH) interface is different from an ordinary QH edge, as the latter has its location determined by the confining potential, while the former can be unpinned and behave like a free string. In this talk, I will elaborate the difference between them through three interfaces formed by (i) the Laughlin state and the vacuum, (ii) the Pfaffian state and the vacuum, and (iii) the Pfaffian and the anti-Pfaffian states. We find that stringlike interfaces propagating freely in the QH system leads to very different dynamical properties from edges. This qualitative difference gives rise to fascinating physics and suggests a different direction for future research on QH physics.