Observation of a non-adiabatic geometric phase for elastic waves

TL;DR

This paper experimentally demonstrates a non-adiabatic geometric phase in elastic waves within a helical waveguide, confirming that the phase arises purely from geometric effects without adiabatic assumptions.

Contribution

The study provides the first experimental observation of a non-adiabatic geometric phase for classical elastic waves, extending geometric phase concepts beyond quantum and optical systems.

Findings

Confirmed non-adiabatic geometric phase in elastic waves

Phase depends solely on geometry, no frequency correction needed

Experimental setup reproduces theoretical predictions accurately

Abstract

We report the experimental observation of a geometric phase for elastic waves in a waveguide with helical shape. The setup reproduces the experiment by Tomita and Chiao [A. Tomita, R.Y. Chiao, Phys. Rev. Lett. 57 (1986) 937-940, 2471] that showed first evidence of a Berry phase, a geometric phase for adiabatic time evolution, in optics. Experimental evidence of a non-adiabatic geometric phase has been reported in quantum mechanics. We have performed an experiment to observe the polarization transport of classical elastic waves. In a waveguide, these waves are polarized and dispersive. Whereas the wavelength is of the same order of magnitude as the helix's radius, no frequency dependent correction is necessary to account for the theoretical prediction. This shows that in this regime, the geometric phase results directly from geometry and not from a correction to an adiabatic phase.