Transport in quantum spin Hall edges in contact to a quantum dot

We study the transport mechanisms taking place in a quantum spin Hall bar with an embedded quantum dot, where electrons localize and experience Coulomb interaction U as well as spin-flip processes {\lambda}. We solve the problem with non-equilibrium Green functions. We focus on the linear response regime and treat the many-body interactions with quantum Monte Carlo. The effects of U and {\lambda} are competitive and the induced transport takes place through different channels. The two mechanisms can be switched by changing the occupation of the dot with a gate voltage.