Does quantum tunnelling need a shaker? Lessons from deterministic walkers and statistical path ensembles

A hydrodynamic walker receives work from a shaker; an isolated quantum particle transmits through a static barrier without driving. We compare scattering, energy ledgers and coherent return. A stationary ground-state-transformed Markov model shares quantum weights and a gap but gives population 0.478393 where unitary evolution gives 1. A vacuum clock supplies no gain sideband. Coloured noise dephases existing coherence; periodic driving can suppress tunnelling. Chemical electron/proton transfer, isotope effects and passive mode dressing add experimental tests. An independent H4 full-CI calculation distinguishes exact gaps from reported geminal splittings. Noise operators, preparation and readout determine which comparisons test a proposed clock mechanism.