Researchers at the Institute for Quantum Computing (IQC) have developed a device that produces twisted neutrons with clearly defined orbital angular momentum for the first time in experimental history.
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This ground-breaking scientific achievement, which was previously thought to be impossible, offers a brand-new way for researchers to investigate the growth of next-generation quantum materials, with applications ranging from quantum computing to discovering and resolving novel problems in fundamental physics.
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.
Dr. Dusan Sarenac, Technical Lead, Transformative Quantum Technologies, University of Waterloo
Dr. Sarenac is also a research associate with IQC.
A device design using neutrons has never before been successfully demonstrated, despite techniques for the experimental production and analysis of orbital angular momentum in photons and electrons being extensively researched. Neutrons have unique properties, so the researchers had to build new tools and develop fresh approaches to working with them.
IQC and Department of Physics and Astronomy faculty member Dr. Dmitry Pushin and his group built microscopic silicon grating structures that resembled forks for use in their experiments. These gadgets are so tiny that more than six million fork dislocation phase gratings can be found in a space that is only 0.5 cm × 0.5 cm.
The single neutrons in the beam start to wind in a corkscrew pattern as they move through this device. A highly specialized neutron camera was used to record the neutrons’ image after they had traveled 19 m. Every neutron had grown into a 10 cm wide donut-shaped signature, the group noticed.
The group’s grating devices produced neutron beams with quantized orbital angular momentum, the first experimental success of its kind, as indicated by the donut pattern of the propagated neutrons, which indicates that they had been put in a special helical state.
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, which will essentially provide an additional quantized degree of freedom.
Dr. Dmitry Pushin, Associate Professor, Department of Physics and Astronomy, University of Waterloo
He further added, “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.”
The study was recently published in the journal Science Advances by Sarenac, Pushin, and associates from the University of Waterloo, the National Institute of Standards and Technology and the Oak Ridge National Laboratory.
TQT, a program of the Canada First Research Excellence Fund, provided funding for the study. The University of Waterloo’s Quantum Nano Fabrication and Characterization Facility produced experimental devices.
Sarenac, D., et al. (2022) Experimental realization of neutron helical waves. Science Advances. doi:10.1126/sciadv.add2002.