Strongly correlated transport in topological Y-junction devices

I analyze electron transport through a Y junction formed by helical edge states of a two-dimensional topological insulator (2DTI), focusing on the strongly interacting regime. An experimentally motivated device geometry and a spin-conserving tunneling Hamiltonian are proposed. I compute the conductance tensor and show that, for specific tunneling phases and strong repulsive interactions ($g<1/2$), transport is governed by an intermediate renormalization group fixed point that interpolates between the weak- and strong-tunneling limits. These results extend previous studies of point-contact tunneling and demonstrate how interactions qualitatively modify the transport properties of multiterminal topological devices.