In an astonishing leap for the field of quantum materials research and neutron science, physicists have achieved something long thought improbable—perhaps even impossible. For the first time, a team of scientists has coaxed a stream of neutrons to travel along a curved path, creating what’s known as a neutron Airy beam. These beams, named after 19th-century English scientist George Biddell Airy, behave in profoundly counterintuitive ways: they arc without external force, resist dispersion, and even “self-heal” after hitting an obstacle.
The groundbreaking feat—documented in a recent issue of Physical Review Letters—represents not just a milestone in fundamental physics but a transformative advance for imaging technologies. With the ability to bend around obstacles and self-correct, these beams could revolutionize how scientists investigate complex materials, revealing hidden structures in pharmaceuticals, pesticides, perfumes, and even cutting-edge quantum devices.
The Strange Tale of Airy Beams: A Brief Primer
To grasp the significance of this breakthrough, one must first understand what makes Airy beams so bizarre and brilliant. Airy beams were first predicted in 1979 and brought to experimental light in the early 2000s with photons (light particles). Named after George Airy, who developed a mathematical function describing the curved path of a point of light in a gravitational field, these beams defy our usual understanding of wave behavior.
Ordinary beams—whether made of light, sound, or particles—tend to disperse and weaken as they move forward. Shine a flashlight and the beam spreads out; throw a stone into a pond and ripples expand outward. Not so with Airy beams. These wave packets maintain their shape and energy concentration over long distances. Moreover, they travel along a parabolic arc, as if guided by invisible hands. And when partially blocked, they reconstruct themselves, as though nothing had interfered with them at all.
Photons and electrons have both been shaped into Airy beams before. But neutrons? That’s a far tougher challenge.
Neutrons: The Unwieldy Particles of the Quantum Zoo
Unlike electrons (which are negatively charged) or photons (which are influenced by optical lenses), neutrons are electrically neutral and have no direct response to magnetic or electric fields. They glide along unperturbed by many forces that affect other particles. That neutrality is a blessing for probing the inner structure of materials—neutrons can sneak past electrons and illuminate atomic nuclei—but it also makes them exceedingly difficult to steer or shape.
Enter the international team of physicists led by Dusan Sarenac of the University at Buffalo. Their collaborators span a globe-spanning effort, including researchers from the National Institute of Standards and Technology (NIST), the University of Maryland, the Paul Scherrer Institute in Switzerland, Oak Ridge National Laboratory in Tennessee, and Germany’s Jülich Center for Neutron Science.
Engineering the Impossible: A Custom-Built Diffraction Grating
Since conventional lenses and magnetic fields couldn’t shape the neutrons, the team had to develop a new kind of “lens” from scratch—one built not from glass or magnets but from exquisitely carved silicon. The breakthrough came in the form of a nanofabricated diffraction grating: a silicon chip just a few millimeters wide but etched with over six million squares, each no more than a micrometer across.
“We knew what we needed,” said Dr. Dmitry Pushin, a physicist at the Institute for Quantum Computing (IQC) at the University of Waterloo. “But we had to invent the roadmap ourselves.”
It took years of simulation and experimentation to perfect the layout. But once the design was locked in, the actual carving of the grating took just 48 hours at the IQC’s nanofabrication facility.
This precisely patterned surface splits an incoming neutron beam into many wavelets that interfere with each other. When these interactions are orchestrated just right, the resulting wavefront behaves as a neutron Airy beam—arcing, self-healing, and refusing to spread.
Physics in the Curve: Why Bent Beams Matter
Now that they exist, what can these beams do?
The immediate benefit lies in neutron imaging. Traditional neutron beams can image the interior of objects in ways that X-rays cannot, revealing hydrogen-rich substances, magnetic ordering, and structural defects in materials. Airy beams add finesse to this process.
According to NIST’s Dr. Michael Huber, these beams could increase resolution, concentrate the beam on specific regions of interest, and maneuver around obstacles that would otherwise obscure a view.
“Being able to curve around something, to look behind it without physically moving anything, changes the game,” said Huber. “It’s like giving neutron imaging a new set of eyes.”
Blending Beams: A New Horizon in Material Science
The research team isn’t stopping at a single beam type. One of their long-term goals is to superimpose neutron Airy beams with other exotic neutron waveforms. For example, they’ve previously created helical neutron beams—waves that twist like corkscrews through space.
By combining these waveforms, they could study one of the most elusive properties in molecular and materials science: chirality.
Chirality, from the Greek kheir for hand, describes structures that are mirror images of each other—like your left and right hands—but are not superimposable. In chemistry, this is crucial. One chiral form of a drug molecule might be therapeutic, while the other is inert or even harmful. The global market for such chiral compounds is massive, exceeding $200 billion annually.
Neutron beams, especially tailored ones like Airy and helical combinations, may offer the most sensitive tools yet for probing chirality in materials.
“Combining curved and twisted beams gives us new information channels,” said Sarenac. “We’re just beginning to explore what’s possible.”
Implications Beyond Imaging: Toward Quantum and Spintronics
Chirality also plays a role in the emerging field of spintronics—where the spin of electrons is harnessed to store and process information. This approach could lead to devices that are faster, more efficient, and more compact than anything built with traditional electronics.
Spin behavior is intimately tied to chirality in some materials. And if scientists can better understand and control how particles interact with chiral structures, it could unlock new pathways in quantum computing—where information is stored in fragile units called qubits.
“Qubits are sensitive to their environment, and chirality is one of those subtle environmental factors,” Huber noted. “Using Airy beams, we could tailor the neutron probe to explore and even influence these effects in situ.”
What’s Next?
The creation of neutron Airy beams marks the dawn of a new era in neutron science. Already, the possibilities are cascading into fields ranging from drug design to quantum information. But as with many scientific firsts, the most exciting applications may be the ones we haven’t yet imagined.
New generations of neutron facilities—some currently under construction—may be designed with beam-shaping components built-in, enabling widespread use of these advanced waveforms. Eventually, neutron Airy beams could become standard tools in the physicist’s toolkit, just as electron microscopes and X-ray spectrometers are today.
Perhaps more intriguingly, they could help unlock deep mysteries in fundamental physics. Could neutron Airy beams be used to test quantum gravity models? Probe dark matter candidates? Simulate exotic quantum phases?
Time—and curved neutron beams—will tell.
Final Thoughts: Riding the Curves of Discovery
It took decades of theoretical work, years of painstaking engineering, and a few days of exquisite nanofabrication to bring the world’s first neutron Airy beams into existence. But this extraordinary advance shows how the fusion of imagination, mathematics, and materials science can bend even the straightest paths of physics—quite literally—into something astonishingly new.
Just as George Airy once bent light into a deeper understanding of optics, today’s physicists are bending neutrons toward new knowledge, new technologies, and new ways of seeing the unseen. As curved beams illuminate the interior of molecules and materials, they may just help illuminate the future of science itself.
Reference: Dusan Sarenac et al, Generation of Neutron Airy Beams, Physical Review Letters (2025). DOI: 10.1103/PhysRevLett.134.153401