A groundbreaking discovery by University of Chicago scientists

A breakthrough can point the way to fundamental insights and new technology.

team of University of Chicago He unveiled the first evidence of “quantum superchemistry” – a phenomenon in which particles in the same quantum state together undergo accelerated interactions. While previously expected, this effect has never been observed in the laboratory before.

Results published in nature physics On July 24, open the door to a new field. Scientists are keenly interested in what are known as “quantum-enhanced” chemical reactions, which could have applications in quantum chemistry, Quantitative statisticsand other technologies, as well as a better understanding of the laws of the universe.

“What we’ve seen is in line with theoretical expectations,” said Cheng Chen, a professor of physics and member of the James Franck Institute and the Enrico Fermi Institute, whose lab conducted the research. “This has been a science goal for 20 years, so it’s a very exciting era.”

Scientists announce the first evidence of “quantum superchemistry” – a phenomenon in which particles in the same quantum state undergo accelerated group interactions. Above, study co-authors Zhendong Zhang (left) and Professor Cheng Chin in the lab. Credit: John Zech

Pose improvement: the process

Chen’s lab specializes in working with molecules that exist at extremely low temperatures. close absolute zeroParticles can correlate so that they are all in the same quantum state – where they can exhibit unusual abilities and behaviors.

It was hypothesized that a group of atoms and molecules in the same quantum state would behave differently during chemical reactions, but the difficulty in organizing the experiment meant that it was never observed.

Chen’s group is experienced at herding atoms into quantum states, but particles are larger and more complex than atoms, so the group had to devise new technologies to counter them.

“How far we can push our understanding and knowledge of quantum geometry, into more complex particles, is a major research direction in this scientific community.”

– Cheng Chen, Professor of Physics

In experiments, scientists cooled cesium atoms and coaxed them into the same quantum state. Next, they watched the atoms interact to form molecules.

In ordinary chemistry, individual atoms collide, and for each collision there is a potential to form a molecule. However, quantum mechanics predicts that atoms in the quantum state perform collective actions instead.

Implications and results

“You no longer treat a chemical reaction as a collision of independent particles, but as a collective process,” Chen explained. “They all interact together, as a whole.”

One consequence is that the reaction occurs faster than it would under normal circumstances. In fact, the more atoms in a system, the faster the reaction.

Another consequence is that the final molecules share the same molecular state. Chen explained that the same molecules in different states can have different physical and chemical properties — but there are times when you want to create a group of molecules in a specific state. In traditional alchemy, you are rolling the dice. “But with this technique, you can direct the molecules into an identical state,” he said.

Shu Nagata, a graduate student and co-author on the paper, added that they saw evidence that the reaction was occurring as a three-body interaction more often than a two-body interaction. That is, three atoms will collide. Two will form a molecule, and the third will remain single. But the third played some role in the reaction.

technological capabilities

This breakthrough marks the beginning of a new era. Although the experiment used twocorn Molecules, there are plans to work with larger and more complex molecules.

“How far we can push our understanding and knowledge of quantum geometry, into more complex particles, is a major research direction in this scientific community,” Chen said.

Some in the field have envisioned using particles as qubits in quantum computers, or in quantum information processing, for example. Other scientists are exploring them as gateways to more precise measurements of fundamental laws and interactions, such as testing fundamental laws of the universe such as symmetry violation.

Reference: “Multibody Chemical Reactions in a Quantitative Decay Gas” by Zhendong Zhang, Shu Nagata, Kai-Xuan Yao, and Cheng Chin, July 24, 2023, Available here. nature physics.
DOI: 10.1038/s41567-023-02139-8

Zhendong Zhang (PhD 22, now at Stanford University) and Kai-Xuan Yao (PhD 22, now at Citadel) were co-authors on the paper.

Funding: National Science Foundation, Air Force Office of Scientific Research, Grainger Graduate Fellowship, Takenaka Foundation Scholarship.