Abstract
The Goos-Hänchen (GH) shift describes a phenomenon in which a specularly reflected beam is translated along the reflecting surface such that the incident and reflected rays no longer intersect at the surface. Using a neutron spin-echo technique and a specially designed magnetic multilayer mirror, we have measured the relative phase between the reflected up and down neutron spin states in total reflection. The relative GH shift calculated from this phase shows a strong resonant enhancement at a particular incident neutron wave vector, which is due to a waveguiding effect in one of the magnetic layers. Calculations based on the observed phase difference between the neutron states indicate a propagation distance along the waveguide layer of 0.65 mm for the spin-down state, which we identify with the magnitude of the giant GH shift. The existence of a physical GH shift is confirmed by the observation of neutron absorption in the waveguide layer. We propose ways in which our experimental method may be exploited for neutron quantum-enhanced sensing of thin magnetic layers.
| Original language | English |
|---|---|
| Article number | 093803 |
| Journal | Physical Review Letters |
| Volume | 134 |
| Issue number | 9 |
| DOIs | |
| State | Published - Mar 7 2025 |
Funding
The IU Quantum Science and Engineering Center is supported by the Office of the IU Bloomington Vice Provost for Research through its Emerging Areas of Research program. Some of this work was supported by the Department of Commerce through Cooperative Agreement No. 70NANB15H259. The experiment was performed on the Larmor instrument at the ISIS Neutron and Muon source (UK) supported by a beam time allocation RB2310496 from the Science and Technology Facilities Council . We would like to thank Amy Navarathna from the TU Delft for performing the X-ray reflectometry measurements. This research was undertaken thanks in part to funding from the Canada First Research Excellence Fund. G.\u2009O. gratefully acknowledges support from the Institute for Advanced Study. Q.\u2009L.\u2009T. would like to thank Dennis Krause for pointing out the connection of this work with interferometry of unstable particles.