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.