Current Echoes

A new echo phenomenon is suggested, which we call the current echo. A disordered one-dimensional tight-binding conductor subject to two very short voltage pulses is considered. While the current response following the first pulse decays due to scattering off the disorder, a delayed current pulse is predicted following the second voltage pulse, its delay being equal to the temporal separation of the two voltage pulses. This prediction is illustrated for an ensemble of finite, disordered chains.