1+1D Chiral Fermions can arise on the edges of 2+1D chiral topological phases, which lead to quantized Hall and thermal Hall effects. Interacting chiral fermions at low energies are usually believed to form an integrable chiral Luttinger liquid. We study the integrability of N identical chiral Majorana fermion modes with generic 4-fermion interactions. We find the system is integrable when N<=6, but becomes quantum chaotic when N>=7. In the large N limit, the system forms a chiral SYK model, which can be solved analytically. The maximal chaos bound is approached at the maximal interaction strength, while the zero-temperature entropy density is zero. Further, we verify the transition from integrability to chaos at N=7 by level statistics numerical calculations. This study reveals a generic new class of scaling invariant physical systems.

Dr. Lian is a condensed matter theorist, with a 2017 PhD, presently a postdoc at the Princeton Center for Theoretical Science. He has broad interests in both more formal aspects of CMT and in those connected to experiment.