A device design using neutrons has never been successfully proven, despite techniques for the experimental synthesis and study of orbital angular momentum in photons and electrons being extensively explored. Neutrons have unique properties, so the researchers had to build new tools and develop new approaches to work with them.

For the first time in experimental history, scientists at the Institute for Quantum Computing (IQC) have developed a device that produces twisted neutrons with a clearly specified orbital angular momentum. This groundbreaking scientific feat, previously thought impossible, provides an entirely new way for scientists to explore the growth of next-generation quantum materials, with applications ranging from quantum computing to discovering and solving new problems in fundamental physics.

Dr. Dusan Sarenac, a research associate at IQC and technical lead of Transformative Quantum Technologies at the University of Waterloo, said: “Neutrons are a powerful probe for the characterization of emerging quantum materials because they have several unique features. They have nanometer-sized wavelengths, electrical neutrality, and relatively large masses. These features allow neutrons to pass through materials that X-rays and light cannot. ”

IQC and faculty member Dr. Dmitry Pushin of the Department of Physics and Astronomy and his group built small silicon lattice structures resembling forks for their studies. These devices are so miniscule that over six million fork dislocation phase gratings can be found in just 0.5 cm by 0.5 cm. The individual neutrons begin to spin in a corkscrew pattern as a stream of a few neutrons passes through this device. A specialized neutron camera captured the pictures of the neutrons after they traveled 19 meters. The group saw that each neutron had grown into a 10 cm wide doughnut-shaped trail.

The donut pattern of the propagated neutrons indicates that they were placed in a special spiral state and that the group’s lattice devices generated neutron beams with quantized orbital angular momentum, the first experimental achievement of its kind.

Dr. Dmitry Pushin, IQC and faculty member of the Department of Physics and Astronomy at Waterloo, said: “Neutrons have been popular in the experimental verification of fundamental physics, using the three easily accessible degrees of freedom: spin, path, and energy. In these experiments, our group has enabled the use of orbital angular momentum in neutron beams, providing an additional quantized degree of freedom In doing so, we are developing a toolbox to characterize and investigate complicated materials needed for the next generation of quantum devices such as quantum simulators and quantum computers.”

Magazine reference:

  1. Dusan Sarenac, Melissa Henerson, et al. Experimental realization of neutron spiral waves. Scientific progress. DOI: 10.1126/sciadv.add2002