Current-current correlations in time domain for a tunnel junction in the quantum regime

We have measured the current fluctuations emitted by a tunnel junction with a very wide bandwidth, from 0.5 to 12 GHz, down to very low temperature T=35mK. This allowed us to perform the spectroscopy (i.e., measure the frequency dependence) of thermal noise (no dc bias, variable temperature), shot noise (low temperature, variable dc voltage bias) and photon-assisted noise (ac bias). Thanks to the very wide bandwidth of our measurement, we can deduce the current-current correlator in time domain. We observe the thermal decay of this correlator as well as its oscillations with a period h/eV, a direct consequence of the effect of the Pauli principle in quantum transport.