Spin-Rotation Coupling Observed in Neutron Interferometry

General ILL Seminar
Organised by College III
Monday, 9 September 2019 at 11h00
Seminar room 7/8, ILL 1

Armin Danner
TU Wien, Karlsplatz 13, 1040 Vienna, armin.danner@tuwien.ac.at

Spin-rotation coupling is an extension of the Sagnac effect, based upon the inertia of intrinsic spin. Its existence was predicted and neutron interferometric experiments to verify it were proposed [1,2]. The latter suggestion was to induce a coupling between the spin and the rotation of a magnetic field. The results of a previous neutron polarimeter experiment are in accordance with the prediction of spin-rotation coupling but can also be explained with the semi-classical Bloch equations.

The technical requirements to conduct a corresponding neutron interferometer experiment are elaborate. As the coupling is small, the required phase stability of interferograms is critical. A spin manipulator is developed [3] which produces a rotating magnetic field while ensuring a non-adiabatic field transition necessary to induce Larmor precession. This is achieved using a geometry without material in the neutron beam to prevent dephasing.

A neutron interferometer experiment is conducted to test for spin rotation coupling [4]. As predicted, the observed phase of the interferograms is linearly dependent on the frequency of the rotating magnetic field. This result is only predicted in quantum mechanics.

[1] B. Mashhoon,Neutron interferometry in a rotating frame of reference, Phys. Rev. Lett. 61,2639 (1988)
[2] B. Mashhoon and H. Kaiser, Inertia of intrinsic spin, Physica B 385–386,  1381 (2006)
[3] A. Danner et al.,Development and perfomance of a miniaturised spin rotator suitable for neutron interferometer experiments,J. Phys. Commun. 3, 035001 (2019)  
[4] A. Danner et al., Spin-Rotation Coupling Observed in Neutron Interferometry, arXiv 1904.07085

You can find a poster on the subject of the seminar in the ILL1 seminar room 7/8

Caterina Michelagnoli
(College III Secretary)

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