We calculate the conductance of a quantum wire with two occupied subbands in presence of a scatterer taking into account the interaction between electrons. We extend the renormalization-group equation for the scattering matrix of the obstacle to the case of intersubband interactions, find its fixed points, and investigate their stability. Depending on the interaction parameters, the conductance may be equal to 0, $e^2/h$, or $2e^2/h$ per spin projection. In some parameter ranges, two stable fixed points may coexist, so the ultimate conductance depends on the properties of the bare scatterer. For spinful electrons, the conductance of the wire may nonmonotonically depend on the Fermi level and temperature.

• Received 11 April 2014
• Revised 29 May 2014

DOI:https://doi.org/10.1103/PhysRevB.89.235412