Proposal of a Realistic Stochastic Rotor Engine Based on Electron Shuttling

Abstract

We propose and analyse an autonomous engine, which combines ideas from electronic transport and selfoscillating heat engines. It is based on the electron-shuttling mechanism in conjunction with a rotational degree of freedom. We focus in particular on the isothermal regime, where chemical work is converted into mechanical work or vice versa, and we especially pay attention to use parameters estimated from experimental data of available single components. Our analysis shows that for these parameters the engine already works remarkably stable, albeit with moderate efficiency. Moreover, it has the advantage that it can be up-scaled to increase power and reduce fluctuations further. arXiv:1903.07500v2 [cond-mat.stat-mech]

The Problem of Engines in Statistical Physics

“…Such fluctuations are not relevant for macroscopic engines with heavy tools, but as the mass of the tool is reduced, the fluctuations become more important, and there must be a limit beyond which the feedback dynamics responsible for the active force is swamped by the thermal noise so that the engine can no longer operate. This has recently been investigated in the context of stochastic thermodynamics [38][39][40]. Our treatment will be somewhat different and based on drawing a distinction between damping forces associated with thermal noise and the force that the load exerts on the tool (which is not associated with thermal fluctuations).…”

“…Acknowledgments: We thank Elizabeth von Hauff for extensive discussions on various issues treated in this work. R.A. thanks Philipp Strasberg for stimulating discussions regarding the methods of [38,39]. A.J.…”

Nanoelectromechanical rotary current rectifier

“…Different realizations of electron shuttles include a harmonic oscillator [12,20,21] or a rotor [22][23][24][25][26] to which the island is attached. While the dynamics of the former are mainly determined by the intrinsic frequency of the oscillator, the lack of such a frequency in the latter leads to complex and rich dynamics, which allow the rotor to act as a motor, sensor or electron pump [25,26]. Such a rotor could be realized by molecules on a surface [27][28][29][30][31][32][33][34][35][36][37] or an electronic island mounted onto a rigid rotor.…”

“…1(a), consists of a single electron transistor where the central island (e.g. a quantum dot) is mounted onto a rotor [25,26]. The position of the island/rotor is specified by the angle θ.…”

“…For individual trajectories the charge q changes stochastically by means of a Poisson process determined by the tunneling rates (2) [43]. For a rotor with moment of inertia I subject to friction with friction constant γ and the electrostatic torque T el (θ, q, t), the stochastic equations of motion take the form [26,45]…”