Ultrashort, high-intensity X-ray laser pulses trigger controlled explosions of molecules – making it possible to capture high-resolution images of molecular structures. Credit: Till Jahnke / Goethe University Frankfurt

Using the world’s most powerful X-ray laser, scientists have filmed atoms performing an eternal quantum dance that never stops — even at absolute zero. This first-ever direct view of zero-point motion reveals that molecules vibrate in beautifully ordered, synchronized patterns instead of random motion.

Most people struggle to make sense of the quantum realm: According to Heisenberg’s uncertainty principle, observing it is like watching a dancer while being allowed to see either their position or their speed, but never both at the same time. Even so, this quantum “dance” is not random. The movements follow strict, well defined patterns.

Within molecules, this unusual behavior has a surprising effect. Even at absolute zero, a temperature at which all motion should vanish, a molecule never becomes completely still. Its atoms continue a faint, continuous motion driven by what scientists call zero-point energy.

Breakthrough in Measuring Zero-Point Motion

For decades, researchers believed these subtle zero-point movements could never be tracked directly. That assumption has now changed. A team at Goethe University Frankfurt and collaborating institutions succeeded in observing them at the European XFEL in Hamburg, Germany, the world’s most powerful X-ray laser. By illuminating individual molecules and recording rapid-fire snapshots of their atoms, the team revealed each atom’s detailed pattern of movement.

Professor Till Jahnke of the Institute for Nuclear Physics at Goethe University Frankfurt and the Max Planck Institute for Nuclear Physics in Heidelberg explains: “The exciting thing about our work is that we were able to see that the atoms don’t just vibrate individually, but that they vibrate in a coupled manner, following fixed patterns. We directly measured this behavior for the first time in individual medium-sized molecules that were also in their lowest energy state. This zero-point motion is a purely quantum mechanical phenomenon that cannot be explained classically.”

Physicists describe these patterns as vibrational modes. Simple molecules containing only a few atoms are relatively easy to characterize, but the situation becomes much more complicated as molecules grow larger. The team examined iodopyridine, which contains eleven atoms and displays 27 different vibrational modes that range across an entire spectrum of motion.

Years of Data Lead to a Breakthrough

“This experiment has a long history,” says Jahnke. “We originally collected the data in 2019 during a measurement campaign led by Rebecca Boll at the European XFEL, which had an entirely different goal. It wasn’t until two years later that we realized we were actually seeing signs of zero-point motion. The breakthrough came through collaboration with our colleagues from theoretical physics from the Center for Free-Electron Laser Science in Hamburg. Benoît Richard and Ludger Inhester, in particular, came up with new analysis methods that elevated our data interpretation to an entirely new level. Looking back, many puzzle pieces had to come together perfectly.”

Imaging Molecules Through Controlled Explosion

Capturing motion on this scale requires an unconventional technique. In Coulomb Explosion Imaging, ultrashort, intense X-ray laser pulses cause molecules to undergo a controlled breakup. The pulse removes many electrons from the molecule, leaving the atoms positively charged. Those atoms rapidly repel each other and fly apart in less than a trillionth of a second. Specialized detectors record the time and location at which the fragments arrive, allowing scientists to reconstruct the molecule’s original structure.

This approach is made possible by the COLTRIMS reaction microscope, a tool refined over several decades by the Atomic Physics group at Goethe University. A custom version designed for the European XFEL was built by Dr. Gregor Kastirke during his PhD research. Kastirke reflects on the achievement: “Witnessing such groundbreaking results makes me feel a little proud. After all, they only come about through years of preparation and close teamwork.”

A New Window Into Quantum Behavior

The team’s findings open a new path toward understanding quantum processes. For the first time, complex zero-point motion patterns in larger molecules can be viewed directly rather than inferred. The success also highlights the capabilities of the COLTRIMS reaction microscope.

“We’re constantly improving our method and are already planning the next experiments,” says Jahnke. “Our goal is to go beyond the dance of atoms and observe in addition the dance of electrons – a choreography that is significantly faster and also influenced by atomic motion. With our apparatus, we can gradually create real short films of molecular processes – something that was once unimaginable.”

Reference: “Imaging collective quantum fluctuations of the structure of a complex molecule” by Benoît Richard, Rebecca Boll, Sourav Banerjee, Julia M. Schäfer, Zoltan Jurek, Gregor Kastirke, Kilian Fehre, Markus S. Schöffler, Nils Anders, Thomas M. Baumann, Sebastian Eckart, Benjamin Erk, Alberto De Fanis, Reinhard Dörner, Sven Grundmann, Patrik Grychtol, Max Hofmann, Markus Ilchen, Max Kircher, Katharina Kubicek, Maksim Kunitski, Xiang Li, Tommaso Mazza, Severin Meister, Niklas Melzer, Jacobo Montano, Valerija Music, Yevheniy Ovcharenko, Christopher Passow, Andreas Pier, Nils Rennhack, Jonas Rist, Daniel E. Rivas, Daniel Rolles, Ilme Schlichting, Lothar Ph. H. Schmidt, Philipp Schmidt, Daniel Trabert, Florian Trinter, Rene Wagner, Peter Walter, Pawel Ziolkowski, Artem Rudenko, Michael Meyer, Robin Santra, Ludger Inhester and Till Jahnke, 7 August 2025, Science. DOI: 10.1126/science.adu2637

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