Rotational friction and diffusion of quantum rotors

TL;DR

This paper develops a quantum master equation to describe how quantum rotors experience decoherence, friction, and diffusion in thermal environments, bridging quantum and classical rotational Brownian motion.

Contribution

It introduces a comprehensive Markovian quantum master equation for various rotors, capturing their decoherence, thermalization, and classical limits in a unified framework.

Findings

The equation describes the evolution of arbitrary initial states toward thermal equilibrium.

Numerical illustrations demonstrate the decoherence and thermalization of linear and planar rotors.

The semiclassical limit reproduces the classical rotational Fokker-Planck equation.

Abstract

We present the Markovian quantum master equation describing rotational decoherence, friction, diffusion, and thermalization of planar, linear, and asymmetric rotors in contact with a thermal environment. It describes how an arbitrary initial rotation state decoheres and evolves toward a Gibbs-like thermal ensemble, as we illustrate numerically for the linear and the planar top, and it yields the expected rotational Fokker-Planck equation of Brownian motion in the semiclassical limit.