Biased impurity tunneling current emission spectrum in the presence of quasi-particle interaction

•We performed theoretical analysis of tunneling current noise spectra through impurity atom.•The role of electron–phonon interaction was carefully analyzed.•Link between quantum noise in tunneling contact and light emission processes was revealed.•Proposed approach can be generalized to more complicated systems.

We performed theoretical investigations of the tunneling current noise spectra through single-level impurity in the presence of quasi-particle (electron-phonon) interaction by means of the non-equilibrium Green function formalism. We demonstrated a fundamental link between quantum noise in tunneling contact and light emission processes. We calculated tunneling current noise spectra through a single level impurity atom both in the presence and in the absence of quasi-particle interaction for a finite bias voltage and identified it as a source of experimentally observed light emission from bias STM contacts. The results turn out to be sensitive to the tunneling contact parameters. Our findings provide important insight into the nature of non-equilibrium electronic transport in tunneling junctions with quasi-particle interaction.