The measured speed in the evanescent regime reflects the spatial decay of the wavefunction, not particle motion

Abstract

The recent paper by Sharoglazova et al. reports an energy-dependent parameter $ν$ extracted from the spatial distribution of photons in a coupled-waveguide experiment. The authors interpret $ν$ as the speed of quantum particles, even in the classically forbidden regime, and claim that its finite value contradicts the Bohmian mechanics prediction of zero particle velocity. This challenge arises from a fundamental misunderstanding of the operational meaning of v within the Bohmian ontological framework. We demonstrate that v quantifies the spatial gradient of the wavefunctions amplitude, a geometric property of the guiding field, not the kinematical velocity of point-like particles. The experiment therefore does not challenge but rather illustrates the clean ontological separation between the wave and particle aspects inherent to Bohmian mechanics.