Neutron beams are used to probe the structure and properties of materials at the atomic level. They are useful in materials science, biology, chemistry, and engineering for developing better drugs, stronger materials, and safer nuclear reactors.
Scientists at the US National Institute of Standards and Technology (NIST) have successfully produced Airy beams using neutrons for the first time. These specialized neutron beams follow a curved path and are capable of investigating materials at the deepest level.
Such beams have unique characteristics, including the ability to accelerate without external forces, resist spreading (nondiffraction) while they travel, and reconstruct their shape after encountering obstacles (self-healing).
“We have introduced and experimentally demonstrated the generation and detection of neutron Airy beams,” the NIST team notes in their study.
The trick to creating neutron Airy beams
A diagram showing the formation of Airy beams. Source: N. Hanacek/NIST
Creating neutron Airy beams has been challenging because neutrons don’t carry charge and interact weakly with matter, making them difficult to steer or focus using conventional optics.
Unlike light or electrons, neutrons cannot be easily shaped with lenses or magnetic fields. Plus, they have low coherence and intensity, which are crucial for generating the structured waveforms needed for an Airy beam.
To overcome all these challenges, the study authors built a customized device incorporating a square of silicon with millions of precisely etched lines. When you zoom into the device, you will find that the lines are arranged within six million tiny squares equally spaced from one another.
This is no ordinary setup. The researchers tested different arrangements for years, and finally, they came across one that split regular neutron beams into Airy beams. “It took us years of work to figure out the correct dimensions for the (silicon) array,” Dmitry Pushin, one of the study authors and a professor at the University of Waterloo, said.
Now, every time a regular neutron beam passes through this optimized silicon device, it is transformed into an Airy beam.
“We’ve known about these strange, self-steering wave patterns for a while, but until now, no one had ever made them with neutrons. 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,” Michael Huber, one of the study authors, said.
One beam, many possibilities
Since neutron Airy beams can follow curved paths and maintain their shape over longer distances, they can improve the resolution of neutron imaging, making it easier to spot fine details inside complex materials without damaging them.
For example, in neutron scattering experiments, Airy beams could be used to focus on specific regions within a sample, such as stress points inside metal parts or the internal structure of batteries and fuel cells.
Another promising area is the combination of Airy beams with other types of neutron beams. This could allow scientists to customize them for specific tasks like detecting magnetic textures in quantum materials, probing defects in advanced semiconductors, and studying chiral structures in biomolecules.
Even if you pick one among these many avenues, the implications are huge. For instance, let’s say scientists are able to control chirality using these beams that it could help us create better drugs and more powerful quantum computers.
“The global market for chiral drugs alone exceeds $200 billion annually, and chiral catalysis techniques underpin the manufacture of many chemical products,” the NIST team notes.
The study is published in the journal Physical Review Letters.