Nanoelectromechanical Oscillator as an Open Quantum System
We examine electron transport through a nanoelectromechanical oscillator coupled to a tunnel junction, as well as the dynamics of this oscillator in the presence of electron tunneling. We analyze two different models, a nano-cantilever, where electrons tunnel directly from one reservoir to another with the transfer matrix elements being modulated by the mechanical oscillations; and a quantum shuttle, when the mechanical oscillator has its own quantized electron states intermediate for the electrons tunneling between the two reservoirs. In both cases, the nano-oscillator is considered as a dynamic subsystem interacting with a heat bath of conducting electrons, and the previously developed theory of open quantum systems is applied. The nonlinear conductances of the systems, the oscillators’ damping rates, and the variances of the oscillator position fluctuations are determined as functions of the applied voltage, temperature, and the electron tunneling length. We also discuss the applications of our analysis to real systems of nano- and molecular electronics.