Phase Imaging with Neutrons

Neutrons are usually considered as small massive particles with a size of about 10^-15 meters. Due to the wave-particle duality of quantum mechanics, however, they can equivalently be considered as matter wave packets whose spatial extent may be large enough to show interference effects similar to what can be observed with visible laser light. Measurements of the neutron wave packet's phase shift induced by different interactions with matter thus have a long and distinguished history in the exploration of the fundamental properties of quantum mechanics. Here we report how a setup consisting of three gratings can be used to produce images depicting the quantum-mechanical phase shifts of neutron wave packets induced by the influence of macroscopic objects. Applications aiming at the imaging of the magnetic domain structures inside macroscopic objects based on the neutrons interaction with the local magnetic field can be envisioned. Furthermore, this work could provide the basis for bridging the gap between imaging and quantum-optical investigations with other matter waves, such as protons, atoms, or molecules.

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