General ILL seminar
organised by College 3
Friday 1st August 2025 at 10h30
Seminar room 110-111, ILL 50, 1st floor
Zoom link: https://ill.zoom.us/j/98964195699?pwd=vPhNT17CAeoDUr7QX4PjfyPnWsHuMU.1
Password: SeminarC3
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“Phase-Grating Moiré Neutron Interferometry”
Dmitry Pushin
dmitry.pushin@uwaterloo.ca
Neutron interferometry is a powerful tool for precise measurements of fundamental constants and material properties, leveraging the neutron’s mass, electric neutrality, and sub-nanometer wavelengths. While the perfect-crystal neutron interferometer, which uses Bragg diffraction to create coherent superpositions, has been successful, its use is limited by complex fabrication, stringent vibration isolation, and narrow wavelength acceptance. In contrast, the phase-grating moiré interferometer (PGMI), first extended to neutrons in 2017, offers significant advantages. Operating with a polychromatic beam and relaxed environmental requirements, the PGMI uses two or three phase-gratings to produce millimeter-scale interference patterns detectable in the far-field, overcoming limitations of perfect-crystal and Talbot-Lau interferometers. The three-PGMI configuration, with gratings separated by meters, achieves large interferometer areas and a magnifying effect, where a micron-scale neutron displacement induces a detectable 2π phase shift. This enables high-precision measurements, such as the Newtonian gravitational constant (big-G) to a potential δG/G of 10⁻⁵, with further optimization underway through advanced neutron diffraction analysis for grating design.
Additionally, by integrating quantum information science, we can engineer neutron wave functions, such as orbital angular momentum states, spin-orbit states, or Airy beams to tailor probes for specific applications, including characterizing topological spin textures for spintronic devices and quantum computing. The PGMI’s versatility and robustness position it as a superior alternative to perfect-crystal interferometry for both fundamental physics and advanced material characterization.
Hanno Filter (College 3 Secretary)
External visitors may ask for a site access to tellier(at)ill.fr