A Quantum Biological Switch Based on Superradiance Transitions

TL;DR

This paper introduces a quantum biological switch leveraging superradiance transitions, demonstrating how quantum effects can control electron transfer directionality in photosynthetic models, with potential applications in quantum biology and bio-inspired devices.

Contribution

It presents a novel quantum switch based on superradiance transitions that can direct electron transfer in bio-molecular chains, a mechanism not previously demonstrated.

Findings

Quantum effects enable electron transfer to weaker sinks with high efficiency.

The switch operates via superradiance and subradiant states.

The device remains reliable at room temperature with realistic data.

Abstract

A linear chain of connected electron sites with two asymmetric sinks, one attached to each end, is used as a simple model of quantum electron transfer in photosynthetic bio-complexes. For a symmetric initial population in the middle of the chain, it is expected that electron transfer is mainly directed towards the strongest coupled sink. However, we show that quantum effects radically change this intuitive "classical" mechanism, so that electron transfer can occur through the weaker coupled sink with maximal efficiency. Using this capability, we show how to design a quantum switch that can transfer an electron to the left or right branch of the chain, by changing the coupling to the sinks. The operational principles of this quantum device can be understood in terms of superradiance transitions and subradiant states. This switching, being a pure quantum effect, can be used as a witness of wave--like behaviour of excitations in molecular chains. When realistic data are used for the photosystem II reaction center, this quantum biological switch is shown to retain its reliability, even at room temperature.