Quantum Ratchets

TL;DR

This paper explores quantum ratchets by analyzing a quantum tight-binding model with an asymmetric potential under external oscillation, revealing finite net currents and parameter-dependent current directions in non-equilibrium steady states.

Contribution

It extends the concept of thermal ratchets to quantum systems and demonstrates quantum effects on current directionality and magnitude.

Findings

Finite net current observed in quantum ratchet system

Current direction varies with system parameters

Quantum effects influence ratchet behavior

Abstract

The concept of thermal ratchets is extended to the system governed by quantum mechanics. We study a tight-binding model with an asymmetric periodic potential contacting with a heat bath under an external oscillating field as a specific example of quantum ratchet. Dynamics of a density operator of this system is studied numerically by using the quantum Liouville equation. Finite net current is found in the non-equilibrium steady state. The direction of the current varies with parameters, in contrast with the classical thermal ratchets.