Strong feedback and current noise in nanoelectromechanical systems

We demonstrate the feasibility of a strong feedback regime for a single-electron tunneling device weakly coupled to an underdamped single-mode oscillator. In this regime, mechanical oscillations are generated and the current is strongly modified whereas the current noise is parametrically big with respect to the Poisson value. This regime requires energy dependence of the tunnel amplitudes. For sufficiently fast tunnel rates the mechanical contribution to current noise can exceed the Poisson value even beyond the strong feedback regime.