Sub-Poissonian phononic population in a nanoelectromechanical system

The properties of the phononic distribution of a mechanical oscillator coupled to a single-electron transistor are investigated in the sequential tunnelling regime. It is shown that for not too strong electron-phonon interaction the electrical current may induce a distribution of phonons with sub-Poissonian statistics, which is characterized by a selective population of few phonon states. Depending on the choice of parameters, such a sub-Poissonian phonon distribution can be accompanied either by a super- or a sub-Poissonian electronic Fano factor.