For the first time, a team of scientists has managed to make neutron beams travel along curved trajectories. Developed by researchers at the National Institute of Standards and Technology (NIST) together with international collaborators, these so-called Airy beams — named after English physicist George Airy — could lead to major advances in the analysis of complex materials like pharmaceuticals, perfumes, and pesticides. Thanks to their ability to bend around obstacles, these beams offer an unprecedented tool for materials research.
“We’ve known about these strange, self-steering wave patterns for a while, but until now, no one had ever made them with neutrons,” said Michael Huber, physicist at NIST and coauthor of the study. “This opens up a whole new way to control neutron beams, which could help us see inside materials or explore some big questions in physics.”
The study was published today in Physical Review Letters. Leading the team was Dusan Sarenac from the University at Buffalo. Key contributions also came from researchers at the Institute for Quantum Computing (IQC) at the University of Waterloo, the University of Maryland, Oak Ridge National Laboratory, Switzerland’s Paul Scherrer Institut, and Germany’s Jülich Center for Neutron Science at Heinz Maier-Leibnitz Zentrum.
Unlike typical beams, which spread out as they move, Airy beams follow parabola-shaped paths without diverging. They can even "self-heal" — if part of the beam is blocked, the wave pattern reconstructs itself after passing the obstacle, continuing on its curved path undisturbed.
Creating Airy beams from neutrons was particularly challenging. Other particles like photons and electrons have been shaped into Airy beams before, but neutrons are harder to manipulate. They are neutral, so electric fields don't affect them, and lenses cannot bend them.
To solve this, the team designed a custom diffraction grating array: a silicon square about the size of a pencil eraser’s tip, etched with millions of microscopic lines. The array consists of over six million squares, each about one micrometer across, separated at carefully calculated distances. This complex structure can split a standard neutron beam into a self-bending Airy beam.
“It took us years of work to figure out the correct dimensions for the array,” said Dmitry Pushin, IQC faculty member and professor at the University of Waterloo. “We only needed about 48 hours to carve the grating at the University of Waterloo’s nanofabrication facility, but before that it took years of a postdoctoral fellow’s time to prepare.”
The potential applications are wide-ranging. Neutron Airy beams could significantly improve imaging techniques like neutron scattering and neutron diffraction, allowing researchers to increase the resolution of scans or focus more precisely on specific parts of a sample.
Huber believes that combining neutron Airy beams with other types of neutron waves could unlock even more possibilities. “We think combining neutron beams could expand the Airy beams’ usefulness,” said Sarenac. “If someone wants Airy beams tailored for some physics or material application, they can tweak our techniques and get them.”
One promising direction would be to merge an Airy beam with a helical neutron wave — a technique the team developed a decade ago. Superimposing these two beams could allow researchers to study materials' chirality, the property where structures exist in left-handed and right-handed forms with different chemical behaviors.
Understanding chirality better could open new doors in many fields. The global market for chiral drugs alone is worth over $200 billion per year, and chiral catalysis plays a central role in producing many chemical products. New ways to control chirality would not only impact pharmaceuticals but also materials science and chemical manufacturing.
Chirality is becoming increasingly relevant in advanced electronics and quantum computing as well. “A material’s chirality can influence how electrons spin, and we could use spin-polarized electrons for information storage and processing,” Huber said. “Controlling it could also help us manipulate the qubits that form the building blocks of quantum computers. Neutron Airy beams could help us explore materials with these capabilities far more effectively.”
The complete work is detailed in the paper: D. Sarenac, O. Lailey, M.E. Henderson, H. Ekinci, C.W. Clark, D.G. Cory, L. DeBeer-Schmitt, M.G. Huber, J.S. White, K. Zhernenkov, and D.A. Pushin. "Generation of Airy Neutron Beams." Physical Review Letters, published online on April 17, 2025, DOI: doi.org/10.1103/PhysRevLett.134.153401.
Glossary
- Airy Beam: A wave beam that propagates along a curved path without dispersing.
- Chirality: A property where an object is not superimposable on its mirror image.
- Diffraction: A physical phenomenon where waves bend around obstacles.
- Diffraction Grating: A structure that splits a beam into multiple waves through a pattern of etchings.
- Neutrons: Subatomic particles with no electric charge, found in atomic nuclei.
- Qubit: The fundamental unit of information in quantum computing.
- Spintronics: Technology that uses the spin of electrons to process information.
- University of Waterloo: A Canadian university known for advanced research in quantum physics.
