Interband transitions and the possibility of current states in systems with electron-hole pairing
Lozovik Yu.E., Yudson V.I.
Interband transitions make states with a homogeneous superfluid flux of particles impossible. At the same time, if the magnitude Tab of the interband transitions does not exceed a critical value Тл, then superfluid states with a coordinate-dependent particle flux and nonzero average flux become possible (this is attainable for spatially separated electrons and holes).