Southwest Quantum Information and Technology

A quantum trajectory picture of single photon absorption and energy transport in photosystem II

Presenting Author: Robert Cook, University of California Berkeley
Contributing Author(s): Liwen Ko, K. Birgitta Whaley

We study the first step in photosynthesis for the limiting case of a single photon interacting with a specific photosynthetic molecular complex, photosystem II (PSII) of green plants. In this talk, we present theoretical results that show how the absorption of a single photon evolves over time given individual realizations of idealized measurements of the outgoing photon fields. This describes a single quantum trajectory whose evolution can be far from equilibrium. Our results show how the (null) detection of the outgoing photon confirms that the system must be in the electronic (excited) ground state, which we show is an effect unique to a single photon input. Our theory includes phonon degrees of freedom and non-radiative channels, which allow us to obtain a microscopic estimate of the uniquely high quantum efficiency of plants to convert absorbed photons into electron-hole pairs. We obtain an average efficiency of 92% under realistic ambient conditions, consistent with bulk experimental measurements. We will also discuss what role the greater molecular environment has on the coherence of the single photon absorption, how this affects the net probability of excitation, and what information could be recovered by continuously measuring the phononic environment.

Read this article online: https://arxiv.org/abs/2110.13811

(Session 5 : Thursday from 5:00 pm - 7:00 pm)