An efficient approach to the quantum dynamics and rates of processes induced by natural incoherent light

TL;DR

This paper introduces a computationally efficient method for simulating quantum system dynamics under natural incoherent light, enabling analysis of excitation processes and quantum coherence effects without solving complex master equations.

Contribution

The authors develop a novel algorithm to simulate quantum dynamics induced by weak incoherent light, bypassing traditional master equation solutions and facilitating studies of biological quantum processes.

Findings

Successfully reconstructed pyrazine's internal conversion dynamics under sunlight.

Enabled assessment of quantum coherence effects on biological time scales.

Provided a scalable method for simulating light-induced quantum processes.

Abstract

In many important cases, the rate of excitation of a system embedded in an environment is significantly smaller than the internal system relaxation rates. An important example is that of light-induced processes under natural conditions, in which the system is excited by weak, incoherent (e.g., solar) radiation. Simulating the dynamics on the time scale of the excitation source can thus be computationally intractable. Here we describe a method for obtaining the dynamics of quantum systems without directly solving the master equation. We present an algorithm for the numerical implementation of this method, and, as an example, use it to reconstruct the internal conversion dynamics of pyrazine excited by sunlight. Significantly, this approach also allows us to assess the role of quantum coherence on biological time scales, which is a topic of ongoing interest.