Conductance fluctuations in metallic nanogaps made by electromigration

We report on low temperature conductance measurements of gold nanogaps fabricated by controlled electromigration. Fluctuations of the conductance due to quantum interferences and depending both on bias voltage and magnetic field are observed. By analyzing the voltage and magnetoconductance correlation functions we determine the type of electron trajectories generating the observed quantum interferences and the effective characteristic time of phase coherence in our device.