Channeling radiation in oriented crystals arises from transitions between quantized transverse bound states in the MeV regime and is strongly affected by thermal diffuse scattering through population transfer and decoherence. A frozen-phonon multislice propagation framework is developed to track a reduced transverse Hilbert space spanned by selected bound-state manifolds using configuration-resolved projection amplitudes. Beyond reproducing transition energies, the method yields reduced manifold density matrices, thermal population kinetics, and depth-resolved coherence metrics. Applied to axial electron channeling in ⟨100⟩ diamond at 16.9 MeV, the results show approximately exponential population loss with strongly state-dependent feeding among low-lying manifolds. For an initial coherent superposition in the degenerate 2p manifold, the intra-manifold purity relaxes toward the maximally mixed limit, consistent with thermally induced random basis rotations. Under 1s initial excitation, population transferred into the 2p and 3d manifolds remains close to maximally mixed, while weak cross-manifold coherences persist. The framework enables quantitative analysis of thermal population dynamics, decoherence, and their links to spontaneous and coherently driven emission observables across a broad range of crystal structures.
@article{arxiv.2602.16529,
title = {Thermal Decoherence and Population Transfer of MeV Channeling Electrons in Diamond},
author = {Tadas Paulauskas},
journal= {arXiv preprint arXiv:2602.16529},
year = {2026}
}