Interferometry has underpinned a century of discoveries, ranging from the disproval of the ether theory to the detection of gravitational waves, offering insights into wave dynamics with unrivaled precision through the measurement of phase relationships. In electronics, phase-sensitive measurements can probe the nature of transmissive topological and quantum states, but are only possible using complex device structures in magnetic fields. Here we demonstrate electronic interferometry in a single-molecule device through the study of nonequilibrium Fano resonances. We show the phase difference between an electronic orbital and a coupled Fabry-Perot resonance are tunable through electric fields, and consequently it is possible to read out quantum information in the smallest materials, offering new avenues for the coherent manipulation down to single molecules.
