Researchers led by Guido Pagano of Rice University used a specialized quantum device to simulate a vibrating molecule and track how energy moves within it. The work, published December 5 in Nature Communications, could improve understanding of the basic mechanisms behind phenomena such as photosynthesis and solar energy conversion.
The researchers modeled a simple molecule with two locations, where one part provides energy and the other part receives, both shaped by vibrations and their environment. By tuning the system, they could directly observe energy moving from donor to acceptor and study how vibrations and energy loss affect that transfer, providing a controlled way to test theories of energy flow in complex materials.
“We can now observe how energy moves in a synthetic molecule, while adjusting each variable independently to see what really matters,” said Pagano, assistant professor of physics and astronomy.
A programmable molecule with trapped ions
The experiment used a chain of trapped atoms made of two isotopes of the same element. One isotope encoded the molecular information, while the other formed the environment around the molecule.
Together with two chosen natural vibrations of the trapped ions, this arrangement allowed a representation of a molecule with a donor site and an acceptor site coupled to two types of molecular vibrations, a simplified representation of real molecular systems with many energy sites and vibrations.
The research team used lasers to create and manipulate the energy states and vibrations in the molecule. In addition, the team introduced a mechanism by which the vibrations lose energy, similar to the way real molecules dissipate energy to their surroundings.
Previous experiments lacked several types of vibrations or failed to control energy loss from the environment. In contrast, this setup included both, using two types of ions and twelve precisely tuned laser frequencies to selectively drive or suppress specific changes in the system.
Once the device was set up, the researchers created a burst of energy at the donor site and tracked its movement toward the acceptor over time.
“By adjusting the interactions between the donor and acceptor, linking them to two types of vibrations and the character of those vibrations, we were able to see how each factor affected the energy flow,” Pagano said.
Monitoring the energy flow under controlled conditions
When the researchers tested their hypothesis, they found that adding more vibrations accelerated energy transfer and opened additional pathways for energy to move. In some cases, these pathways reinforced each other, allowing energy to flow more efficiently even as the system lost energy to its surroundings.
They also found that when the vibrations differed from each other, the energy transfer became less sensitive to mismatches between donor and acceptor energies. This expanded the range over which efficient transfer could take place.
“The results show that vibrations and their environment are not simply background noise, but can actively direct the energy flow in unexpected ways,” said Pagano.
Unlike traditional chemical experiments, where multiple factors are intertwined and difficult to separate, the quantum simulator allows independent adjustment of each parameter. This clarity helps disentangle competing effects and test fundamental concepts in a controlled environment, Pagano said.
Implications for practical devices
These findings could help design organic solar cells, molecular wires and other devices that rely on efficient energy or charge transfer. By understanding how vibrations affect this current under different conditions, engineers can develop materials that harness these quantum effects rather than being hindered by them.
“These are the kinds of phenomena that physical chemists have theorized as existing, but until now could not be easily isolated experimentally, especially not in a programmable way,” said Visal So, a Rice doctoral student and first author of the study.
Co-authors include Rice’s Midhuna Duraisamy Suganthi, Mingjian Zhu, Abhishek Menon, George Tomaras and Roman Zhuravel, along with Han Pu, professor of physics and astronomy, Peter Wolynes, the DR Bullard-Welch Foundation professor of chemistry, and Jose Onuchic, the Harry C. and Olga K. Wiess Chair of Physics.
The Welch Foundation, Office of Naval Research, National Science Foundation CAREER Award, Army Research Office, and Department of Energy supported this research.
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