Breakthrough of ‘quantum superchemistry’: A pioneering discovery by scientists at the University of Chicago

“What we saw matches the theoretical predictions,” said Cheng Chin, a professor of physics and a member of the James Franck Institute and the Enrico Fermi Institute, whose lab conducted the research. “It’s been a scientific goal for 20 years, so it’s a very exciting time.”

Scientists have announced the first evidence of “quantum superchemistry” – a phenomenon where particles in the same quantum state experience collective accelerated reactions. Above, study co-authors Zhendong Zhang (left) and Professor Cheng Chin in the lab. 1 credit

Bose improvement: the process

Chin’s lab specializes in working with particles held at very, very low temperatures. Close

” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>absolute zeroparticles can bind together so that they are all in the same quantum state, where they can display unusual abilities and behaviors.

It had been theorized that a group of atoms and molecules in the same quantum state would behave differently in chemical reactions, but the difficulty in orchestrating the experiment meant it had never been observed.

Chin’s group is used to grouping atoms into quantum states, but molecules are larger and much more complex than atoms. The group therefore had to invent new techniques to confuse them.

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

– Cheng Chin, professor of physics

In the experiments, the scientists cooled cesium atoms and brought them into the same quantum state. Then they observed that atoms reacted to form molecules.

In ordinary chemistry, individual atoms would collide, and there is a probability that each collision would form a molecule. However, quantum mechanics predicts that atoms in a quantum state perform actions collectively instead.

Implications and consequences

“You no longer treat a chemical reaction as a collision between independent particles, but as a collective process,” Chin explained. “All react together, as a whole.”

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

Another consequence is that the final molecules share the same molecular state. Chin 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 batch of molecules in a specific state. In traditional chemistry, you roll the dice. “But with this technique, you can orient molecules into an identical state,” he said.

Shu Nagata, a graduate student and co-author of the paper, added that they had seen evidence that the reaction occurred more often as a three-body interaction than as a two-body interaction. two bodies. That is, three atoms would collide; two would form a molecule, and the third would remain unique. But the third played some role in the reaction.

Technological possibilities

This breakthrough marks the beginning of a new era. Although the experiment used two simple

” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”> atom molecules, it is intended to work with larger and more complex molecules.

“How far we can push our understanding and knowledge of quantum engineering, into more complicated molecules, is a major research direction in this scientific community,” Chin said.

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

Reference: “Many-Body Chemical Reactions in Quantum Degenerate Gas” by Zhendong Zhang, Shu Nagata, Kai-Xuan Yao, and Cheng Chin, July 24, 2023, Natural 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 also co-authors of the paper.

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