Edge states of integral quantum Hall states versus edge states of   antiferromagnetic quantum spin chains
  Using the network model representation, it is shown that the edge states of finite-size integral quantum Hall liquid can be regarded as the edge states of an SU$(2N)$ open antiferromagnetic quantum spin chain in the $N \rightarrow 0$ limit. The structures of edge states in both cases of integer quantum Hall liquid and an SU$(2N)$ antiferromagnetic quantum spin chain are compared and the relations between them are pointed out. This correspondence is used to give qualitative arguments in favor of the recent results on two-dimensional electron systems coupled in layers with a large perpendicular magnetic field. In particular, it is shown that the absence of the localization in the two-dimensional chiral surface state of the integral quantum Hall liquid in the case of the finite-size coupled system can be explained by the absence of the gap in the excitation spectrum of an SU$(2N)$ ferromagnetic quantum spin chain in the $N \rightarrow 0$ limit. 
Yong Baek Kim (AT&T Bell Labs.)