Critical currents and giant non-dissipative drag for superfluid electron-hole pairs in quantum Hall multilayers

Superfluid properties of electron-hole pairs in a quantum Hall four-layer system are investigated. The system is considered as a solid-state realization of a two-component superfluid Bose gas with dipole-dipole interaction. One superfluid component is formed in the top bilayer and the other component-in the bottom one. We obtain the dispersion equation for the collective mode spectrum and compute the critical parameters ( the critical interlayer distance and the critical currents) versus the filling factor. We find that the critical currents of the components depend on each other. The maximum critical current of a given component can be reached if the current of the other component is equal to zero. The non-dissipative drag effect between the components is studied. It is shown that in the system considered the drag factor is very large. Under appropriate conditions it can be about 10%, which is at least three orders of magnitude larger than one predicted for two-component atomic Bose gases.