Anomalous Coulomb drag between a normal metal and a superconductor

A novel Coulomb drag effect between an active monolayer graphene and a passive superconducting LAO/STO interface has been recently observed in experiment. In the superconducting transition regime of the LAO/STO interface, the passive-to-active ratio can reach ~1 at optimal gate voltage and the sign is independent of the carrier type in the graphene layer. The anomalous drag responses can be successfully described by the model of an normal conductor dragging a Josephson junction array via Coulomb fields, and the so-termed Josephson-Coulomb (JC) drag mechanism originates from the interactions between the substantially enhanced dynamical quantum fluctuations of the superconducting phases in the passive layer and the normal electrons in the active layer. In this talk, we present a detailed theoretical description of the JC drag effects in the nonequilibrium many-body formalism. We will see that the JC drag belongs to the broad spectrum of the energy drag, and, more importantly, it manifests the unique role of quantum fluctuations in dominating the interlayer processes. The JC drag devices may also contribute an important piece to modern SC electronics working as current (voltage) transformers or terahertz radiators.