Time-resolved quantum correlations in electronic noise

Abstract

The statistics of quantum transport in nanostructures can be tailored by a time-dependent bias voltage $V(t)$. We demonstrate experimentally how correlations of current fluctuations at two different times $t$ and $t+\tau$ depend on the shape of $V(t)$ via the phase accumulated by the electronic wavefunctions between $t$ and $t+\tau$. For this we measure the current-current correlation of the shot noise of an ac+dc biased tunnel junction using a 10 GHz bandwidth, time-resolved detection. Our result allows to explore correlations within a single excitation period. It demonstrates the counterpart of the ac Josephson effect in superconducting junctions, to a normal, non-superconducting mesoscopic device.