Non-symmetrized noise in a quantum dot: interpretation in terms of photon emission and coherent superposition of scattering paths

We calculate the non-symmetrized current noise in a quantum dot connected to two reservoirs in the presence of interactions in the dot by using non-equilibrium Green function technique. We show that both the self-noise (inside a single reservoir) and the cross-noise (between both reservoirs) are expressed in terms of transmission amplitude and coefficient through the barriers. We identify the different photon emission processes involved in each contribution to the self-noise and highlight the fact that when there are several physical processes, the contribution results from a coherent superposition of scattering paths. Varying the gate and bias voltages, we discuss the profile of the differential Fano factor in the light of recent experiments.