Experimental realization of helical neutron waves

Science Advances (2022). DOI: 10.1126/sciadv.add2002″ width=”800″ height=”476″/>

Holographic approach to the generation of neutron helical wavefronts carrying well-defined OAMs. (A) SEM images characterizing the array of hairpin dislocation phase gratings used to generate the helical neutron wavefronts. The arrays covered an area of ​​0.5 cm by 0.5 cm and consisted of 6,250,000 individual 1 μm by 1 μm hairpin dislocation phase gratings that had a period of 120 nm, had a height of 500 nm and were separated by 1 μm on each side. Three arrays with topological charges of q = 0 (standard grating profile), q = 3 (shown here), and q = 7 were used in the experiment. (B) Each phase grating generates a diffraction spectrum consisting of diffraction orders (m) which carry a well-defined OAM value of ℓ = mħq. (C) The far-field intensity is the sum of the signal from all individual hairpin dislocation phase gratings. An example of the collected small-angle neutron scattering (SANS) data is shown. Credit: The progress of science (2022). DOI: 10.1126/sciadv.add2002

For the first time in experimental history, researchers at the Institute for Quantum Computing (IQC) have created a device that generates twisted neutrons with well-defined orbital angular momentum. Previously thought impossible, this breakthrough scientific achievement offers researchers a new avenue to study the development of next-generation quantum materials with applications ranging from quantum computing to identifying and solving new problems in fundamental physics.

‘Neutrons are a powerful probe for the characterization of emerging quantum materials because they have several unique characteristics,’ said Dr. Dusan Sarenac, Research Associate with IQC and Technical Lead, Transformative Quantum Technologies at the University of Waterloo. “They have nanometer-sized wavelengths, electrical neutrality, and a relatively large mass. These characteristics mean that neutrons can pass through materials that X-rays and light cannot.”

While methods for the experimental production and analysis of orbital angular momentum in photons and electrons are well studied, a device design using neutrons has never been demonstrated until now. Due to their distinct characteristics, researchers had to build new devices and create new methods of working with neutrons.

In their experiments, Dr. Dmitry Pushin, IQC and faculty member in the Department of Physics and Astronomy at Waterloo, and his team have built microscopic fork-like silicon lattice structures. These devices are so tiny that in an area just 0.5 cm by 0.5 cm, there are over six million individual hairpin dislocation phase gratings.

When a beam of single neutrons passes through this device, the single neutrons begin to spiral. After traveling 19 meters, a neutron image was captured using a special neutron camera. The team observed that each neutron had expanded to form a donut-like signature 10cm wide.

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

“Neutrons have been popular in the experimental verification of fundamental physics, using the three easily accessible degrees of freedom: spin, path and energy,” Pushin said.

‘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. In doing so, we are developing a toolbox for characterizing and examining complex materials required for the next generation of quantum devices such as quantum simulators and quantum computers”.

The article Experimental realization of helical neutron waves by Sarenac, Pushin and collaborators of the University of Waterloo, the National Institute of Standards and Technology and the Oak Ridge National Laboratory was recently published in the journal The progress of science.

More information:
Dusan Sarenac et al, Experimental Realization of Helical Neutron Waves, The progress of science (2022). DOI: 10.1126/sciadv.add2002

Provided by the University of Waterloo

Citation: New Quantum Tool: Experimental Realization of Helical Neutron Waves (2022 Nov 21) Retrieved Nov 23, 2022 from https://phys.org/news/2022-11-quantum-tool-experimental-neutron-helical.html

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