# Abstract – Armin Danner

April 11, 2019 1:28 pm**Spin-Rotation Coupling Observed in Neutron Interferometry **

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.

**References**

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