Drag conductance induced by neutral-mode localization in fractional quantum Hall junctions

The fractional quantum Hall (FQH) effect gives rise to abundant topological phases, presenting an ultimate platform for studying the transport of edge states. Generic FQH edge contains multiple edge modes, commonly including the counterpropagating ones. Recent experimental advances in engineering novel devices with interfaces of different FQH states enable transport measurements of FQH edges and edge junctions also featuring counterpropagating modes. In such a platform with counterpropagating modes, the influence of Anderson localization on transport is explored. By using a reduced theory of the edge after localization, we develop a general framework for transport. We then apply this framework to a junction of two 2/3 FQH edges that with no charge tunneling between them, may exhibit Anderson localization of neutral modes. We identify two competing localization channels, “neutral-mode superconductivity” and “neutral-mode backscattering”. In particular, we find that the four-terminal conductance reveals a strong quantized drag between the edges induced by neutral-mode localization. The two localization channels lead to opposite signs of the drag conductance, equal to ±e^2/(4h), which can also be interpreted as a special type of Andreev scattering. ... mehrThis strong quantized drag effect is a consequence of coherent localization processes.