Quantum device simulates chemical reaction in super slow motion

Gif showing one red blob turning into two on graph
Researchers constructed a movie of the ion’s evolution around the conical intersection. Each frame of the GIF shows an image outlining the probability of finding the ion at a specific set of coordinates.

A quantum device has been used to simulate a chemical reaction allowing scientists to observe in milliseconds what happens in femtoseconds in nature.

A millisecond is one thousandth of a second and a femtosecond is one million billionth of a second.

The simulation allowed scientists to see for the first time the interference pattern in an atom caused by a ‘conical intersection’ – a phenomenon vital to rapid photo-chemical processes such as photosynthesis and light harvesting in human vision.

University of Sydney chemists and physicists generated a simulation of a conical intersection slowed by a factor of 100 billion times.

Their results are published in Nature Chemistry.

Two people in quantum computer lab
Vanessa Olay Agudelo and Dr Christophe Valahu in front of the quantum computer in the Sydney Nanoscience Hub used in the experiment. Credit: Stefanie Zingsheim.

“It is by understanding these basic processes inside and between molecules that we can open up a new world of possibilities in materials’ science, drug design, or solar energy harvesting,” says joint lead researcher Vanessa Olaya Agudelo, a PhD student at the University of Sydney.

“It could also help improve other processes that rely on molecules interacting with light, such as how smog is created or how the ozone layer is damaged.”

Chemists have tried to observe such processes since the 1950s.

To get around the problem of how rapidly conical intersections in reactions occur, the quantum researchers used a trapped ion quantum simulator in a new way to map the complicated chemistry onto a relatively small quantum device, and slow the process down by a factor of 100 billion.

“Using our quantum computer, we built a system that allowed us to slow down the chemical dynamics from femtoseconds to milliseconds. This allowed us to make meaningful observations and measurements,” Agudelo says. “This has never been done before.”

“Until now, we have been unable to directly observe the dynamics of ‘geometric phase’; it happens too fast to probe experimentally,” says joint lead author Dr Christophe Valahu. “Using quantum technologies, we have addressed this problem.”

Valahu likens the experiment to simulating aerodynamics around a plane wing in a wind tunnel, saying: “Our experiment wasn’t a digital approximation of the process – this was a direct analogue observation of the quantum dynamics unfolding at a speed we could observe.”

“This exciting result will help us better understand ultrafast dynamics – how molecules change at the fastest timescales,” says co-author Associate Professor Ivan Kassal from the University of Sydney Nano Institute.

The quantum computer used is in the Quantum Control Laboratory and its use in the experiment led by Dr Ting Rei Tan.

“This is a fantastic collaboration between chemistry theorists and experimental quantum physicists,” says Tan, a co-author on the paper. “We are using a new approach in physics to tackle a long-standing problem in chemistry.”

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