Quantum noise in ac-driven resonant-tunneling double barrier structures: Photon-assisted tunneling vs. electron anti-bunching

We study the quantum noise of electronic current in a double barrier system with a single resonant level. In the framework of the Landauer formalism we treat the double barrier as a quantum coherent scattering region that can exchange photons with a coupled electric field, e.g. a laser beam or a periodic ac-bias voltage. As a consequence of the manyfold parameters that are involved in this system, a complicated step-like structure arises in the non-symmetrized current-current auto correlation spectrum and a peak-like structure in the cross correlation spectrum with and without harmonic ac-driving. We present an analytic solution for these noise spectral functions by assuming a Breit-Wigner lineshape. In detail we study how the correlation functions are affected by photo-assisted tunneling (PAT) events and discuss the underlying elementary events of charge transfer where we identify a new kind of contribution to shot-noise. This enables us to clarify the influence of a not centered irradiation of such a structure with light in terms of contributions originating from different sets of coherent scattering channels. Moreover we show how the noise is influenced by acquiring a scattering phase due to the complex reflection amplitudes that are crucial in the Landauer approach.