Coherence turned on by incoherent light

Vyacheslav N Shatokhin,Frank Schlawin,Andreas Buchleitner,Mattia Walschaers

doi:10.1088/1367-2630/aaf08f

Abstract

One of the most pertinent problems in the debate on non-trivial quantum effects in biology concerns natural photosynthesis. Since sunlight is composed of thermal photons, it was argued to be unable to induce quantum coherence in matter, and that quantum mechanics is therefore irrelevant for the dynamical processes following photoabsorption. Our present analysis of a toy ‘molecular aggregate’—composed of two dipole–dipole interacting two-level atoms treated as an open quantum system—however shows that incoherent excitations indeed can trigger persistent, coherent dynamics in both the site and the exciton bases: we demonstrate that collective decay processes induced by the dipole–dipole interactions create coherent intermolecular transport—regardless of the coherence properties of the incoming radiation. Our analysis shows that the steady state coherence is mediated by the population imbalance between the molecules and, therefore, increases with the energy difference between the two-level atoms. Our results establish the importance of collective decay processes in the study of ultrafast photophysics, and especially their potential role to generate stationary coherence in incoherently driven quantum transport.

Highlights

A detailed understanding of the microscopic processes which underlie natural photosynthesis represents an important and intriguing source of inspiration for technologies which seek to efficiently capture, transform, and store solar energy [1, 2]
It is a priori crucial to distinguish the coherence observed in photon echoes [12] from coherence which may arise in non-equilibrium open system quantum dynamics—as we will outline below
We have studied the dynamics of the electronic coherence of a toy ‘molecular aggregate’ composed of two closely located two-level atoms coupled to a vacuum reservoir and excited by an incoherent field

Summary

November 2018

Vyacheslav N Shatokhin, Mattia Walschaers, Frank Schlawin and Andreas Buchleitner. Since sunlight is composed of thermal photons, it was argued to be unable to this work must maintain attribution to the induce quantum coherence in matter, and that quantum mechanics is irrelevant for the author(s) and the title of dynamical processes following photoabsorption. Composed of two dipole–dipole interacting two-level atoms treated as an open quantum system—. Shows that incoherent excitations can trigger persistent, coherent dynamics in both the site and the exciton bases: we demonstrate that collective decay processes induced by the dipole–. Our analysis shows that the steady state coherence is mediated by the population imbalance between the molecules and, increases with the energy difference between the two-level atoms. Our results establish the importance of collective decay processes in the study of ultrafast photophysics, and especially their potential role to generate stationary coherence in incoherently driven quantum transport

Introduction

Unraveled dynamics

Conclusion