Scientists developed a new quantum tool in a groundbreaking experiment

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

Scientists at the Institute for Quantum Computing (IQC) have developed a device that produces twisted neutrons with clearly specified orbital angular momentum for the first time in experimental history. This groundbreaking scientific achievement, which was previously thought impossible, offers a brand-new way for scientists to investigate the growth of next-generation quantum materials, with applications ranging from quantum computing to discovering and resolving novel problems in fundamental physics.

Dr. Dusan Sarenac, a research associate with 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 a relatively large mass. These features mean neutrons can pass through materials that X-rays and light cannot.”

IQC and Department of Physics and Astronomy faculty member Dr. Dmitry Pushin and his group built small silicon grating structures resembling forks for their studies. These devices are so minuscule that more than six million fork dislocation phase gratings can be found in only 0.5 cm by 0.5 cm. The individual neutrons start twisting in a corkscrew pattern as a stream of single neutrons passes through this device. A specialized neutron camera recorded the neutrons’ pictures after they traveled 19 meters. The group noticed that every neutron had grown into a 10 cm wide donut-shaped trace.

The donut pattern of the propagated neutrons indicates that they have been put in a special helical state and that the group’s grating devices have generated neutron beams with quantized orbital angular momentum, the first experimental achievement of its kind.

Dr. Dmitry Pushin, IQC and Department of Physics and Astronomy faculty member 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 examine complicated materials needed for the next generation of quantum devices such as quantum simulators and quantum computers.”

Journal Reference:

1. Dusan Sarenac, Melissa Henerson, et al. Experimental realization of neutron helical waves. Science Advances. DOI: 10.1126/sciadv.add2002