A study from Rice University, published in PRX Quantum Oct. 1, has found that energy transfers more quickly between molecular sites when it starts in an entangled, delocalized quantum state instead of from a single site. The discovery could lead to the development of more efficient light-harvesting materials that enhance the conversion of energy from light into other forms of energy.
Many biochemical processes, including photosynthesis, depend on rapid and efficient energy transfer following absorption. Understanding how quantum mechanical effects like entanglement influence these processes at room temperature could significantly change our approach to creating artificial systems that mimic nature’s efficiency.
“Delocalizing the initial excitation across multiple sites accelerates the transfer in ways that starting from a single site cannot achieve,” said Guido Pagano, the study’s corresponding author and assistant professor of physics and astronomy.
Model and method
The study uses a simplified model molecule consisting of two regions: a donor, where energy is initially absorbed, and an acceptor, where the energy must eventually arrive. Energy can hop between sites within each region; although longer hops are less likely, they are still included in the model. The model also accounts for interactions with the environment, which can couple to the molecule’s vibrations and affect the energy transfer process.
A key focus of the research was determining whether it is more effective for energy to start entirely at one donor site or in a delocalized or entangled superposition spread over two or more donor sites. The researchers explored whether this quantum mechanical property impacts transfer speed in a system with long-range interactions.
“Starting in a delocalized quantum state provides the system with more pathways,” Pagano said. “Our simulations indicate that this added coherence allows for quicker transfer to the acceptor, even in the presence of environmental noise.”
Findings and implications
The research team discovered that when energy begins in an entangled initial state, transfer to the acceptor occurs significantly faster than in scenarios where the energy starts at a single site. This finding holds true across various model parameters, including the strength of environmental coupling, the range of interactions between sites and disorder within the system.
“This suggests that nature may be using entanglement and coherence to optimize the speed of excitation transfer, thereby enhancing the robustness of this process,” Pagano said.
Although the model is intentionally minimal, the researchers argue that its implications extend to more complex molecular systems. They propose that experimental tests could be conducted using controllable quantum platforms such as trapped-ion systems to simulate the physics of molecular energy transfer.
“Our goal is to bridge the abstract world of quantum information with the tangible mechanisms observed in biology,” said Diego Fallas Padilla, the study’s first author and Rice alumnus. “This study serves as a step toward illustrating that quantum coherence is not just a theoretical curiosity but a practical component of nature’s design.”
Co-authors of the study include Rice’s Visal So, Abhishek Menon, Roman Zhuravel and Han Pu. The research was supported by the Welch Foundation Award, the Office of Naval Research Young Investigator Program, the National Science Foundation CAREER Award, the Army Research Office, and the Office of Naval Research.