Negative Differential Resistivity from Holography

Negative differential resistivity (NDR) in a (3+1)-dimensional quantum system of strongly correlated charge carriers is theoretically reproduced by using the AdS/CFT correspondence. Our system is microscopically defined, and the analysis does not rely on any phenomenological models of NDR mechanism. The interaction between the heat reservoir and the nonequilibrium charge carriers is also taken into account. The system realizes insulation due to the formation of the neutral bound states of the charge carriers at low temperatures. However, the insulation is broken and the field-induced conductor phase appears by applying the external electric field greater than the critical value. We find that the NDR appears right above the critical electric field in this phase, and the pair creation of the charge carriers is crucial to realize the NDR. The present result suggests a possibility to observe a similar NDR in excitonic insulators or in the strongly interacting quark-gluon plasma, where the insulation originates in the formation of the neutral bound states.