Cascade of Quantum Phase Transitions in Tunnel-Coupled Edge States

Abstract

We report on the cascade of quantum phase transitions exhibited by tunnel-coupled edge states across a quantum Hall line junction. We identify a series of quantum critical points between successive strong and weak tunneling regimes in the zero-bias conductance. Scaling analysis shows that the conductance near the critical magnetic fields $B_c$ is a function of a single scaling argument $|B-B_c|T^{-\kappa }$, where the exponent $\kappa =0.42$. This puzzling resemblance to a quantum Hall-insulator transition points to importance of interedge correlation between the coupled edge states.

4 pages, 3 figures