Molecular Makeover: Scientists Uncover a Way to Break and Rebuild Molecules with Light

2024-10-21

 

In a groundbreaking study, researchers from Purdue University and the Max-Planck Institute for Quantum Optics in Munich have revealed an unexpected twist in molecular physics: they can break molecules apart using laser light, only to reform them in a new, stable state. This discovery defies conventional chemistry, where severing chemical bonds typically results in the destruction of the molecule.

According to Valentin Walther, Assistant Professor of Physical Chemistry and Physics and Astronomy, and member of the Quantum Science and Engineering Institute (PQSEI) at Purdue University, these newly formed molecular states remain stable as long as the laser light is present.

“The molecules exist in a quantum superposition of being both intact and broken apart,” Walther explains. "Remarkably, this laser-induced binding can assemble multiple atoms into larger molecules, something not possible without the laser's influence."

The study, published in PRX Quantum, is the latest collaboration between Walther’s team and researchers led by Professor Immanuel Bloch at the Max-Planck Institute. Walther, who has worked with the Munich group since 2018, is a joint first author on the paper and played a crucial role in interpreting unexpected experimental results. His theoretical models not only explained the findings but predicted additional molecular structures that were confirmed by the data.

Central to the research is the exploration of Rydberg states—highly excited electronic orbitals that enable novel molecular behaviors. These states create extremely weak bonds, about a million times weaker than typical chemical bonds, allowing the formation of "macrodimers," molecules 1,000 times larger than ordinary molecules. First discovered in 2019, these macrodimers are comparable in size to bacteria despite consisting of just two atoms.

The experiments revealed that laser light can form and break these fragile bonds on timescales matching the vibrational motion of the atomic pairs, resulting in quantum mechanical superpositions of the molecule and its dissociated components. This ability to manipulate molecules in slow motion opens up new avenues for studying molecular binding and controlling chemical dynamics.

“This breakthrough offers a unique opportunity to observe and manipulate molecular interactions with extraordinary precision,” says Walther. “We’ve taken the first steps toward assembling molecules with light and aim to extend these techniques to bind even more atoms. These developments could be instrumental in creating large-scale entanglement for quantum information technologies based on neutral atom lattices.”

The Munich research team included Simon Hollerith, now a postdoctoral researcher at Harvard University, Johannes Zeiher, and Immanuel Bloch. Their joint efforts continue to push the boundaries of quantum science, promising new insights and technological advances in molecular physics and quantum computing.

 

About the Department of Physics and Astronomy at Purdue University  

Purdue’s Department of Physics and Astronomy has a rich and long history dating back to 1904. Our faculty and students are exploring nature at all length scales, from the subatomic to the macroscopic and everything in between. With an excellent and diverse community of faculty, postdocs and students who are pushing new scientific frontiers, we offer a dynamic learning environment, an inclusive research community and an engaging network of scholars.  

Physics and Astronomy is one of the seven departments within the Purdue University College of Science. World-class research is performed in astrophysics, atomic and molecular optics, accelerator mass spectrometry, biophysics, condensed matter physics, quantum information science, and particle and nuclear physics. Our state-of-the-art facilities are in the Physics Building, but our researchers also engage in interdisciplinary work at Discovery Park District at Purdue, particularly the Birck Nanotechnology Center and the Bindley Bioscience Center. We also participate in global research including at the Large Hadron Collider at CERN, many national laboratories (such as Argonne National Laboratory, Brookhaven National Laboratory, Fermilab, Oak Ridge National Laboratory, the Stanford Linear Accelerator, etc.), the James Webb Space Telescope, and several observatories around the world.   

About Purdue Chemistry

The Tarpo Department of Chemistry is internationally acclaimed for its excellence in chemical education and innovation, boasting two Nobel laureates in organic chemistry, the #1 ranked analytical chemistry program, and a highly successful drug discovery initiative that has generated hundreds of millions of dollars in royalties. 

 

About Purdue University  

Purdue University is a public research institution demonstrating excellence at scale. Ranked among top 10 public universities and with two colleges in the top four in the United States, Purdue discovers and disseminates knowledge with a quality and at a scale second to none. More than 105,000 students study at Purdue across modalities and locations, including nearly 50,000 in person on the West Lafayette campus. Committed to affordability and accessibility, Purdue’s main campus has frozen tuition 13 years in a row. See how Purdue never stops in the persistent pursuit of the next giant leap — including its first comprehensive urban campus in Indianapolis, the Mitch Daniels School of Business, Purdue Computes and the One Health initiative — at https://www.purdue.edu/president/strategic-initiatives.

 

 

Contributors:   

Valentin Walther, Assistant professor of Physics and Astronomy and Physical Chemistry at the Purdue University College of Science

Cheryl Pierce, Lead Marketing and Public Relations Specialist at the Purdue University College of Science

Graphic by Cheryl Pierce using elements from Adobe Images.