The fibre operators in the Bloch-Floquet decomposition of periodic magnetic pseudo-differential operators
Horia D. Cornean, Bernard Helffer, Radu Purice
TL;DR
The paper extends Bloch-Floquet theory to periodic magnetic pseudodifferential operators with periodic vector potentials, providing explicit fibre-wise distribution kernels on the torus and as matrices on $\ell^2(\Gamma_*)$. It shows that the fibre operators are toroidal pseudodifferential operators and constructs a symmetric toroidal Weyl calculus, connecting the fibre decomposition to a principal-bundle viewpoint over the torus. A key technical achievement is the explicit derivation of fibre kernels and the demonstration that, for zero-mean flux, magnetic quantization coincides with standard Weyl quantization, enabling a unified torus-calculus approach. These results furnish a robust framework to analyze spectral properties, domain decomposition, and regularity of fibre operators, with potential applications to multi-field magnetic scenarios and torus-based quantum systems.
Abstract
We study the structure of the fibre operators corresponding to periodic magnetic pseudo-differential operators having periodic magnetic potentials. We obtain explicit formulas for their distribution kernel, both when these fibres are seen as operators on the $d$-dimensional torus, and also when they are seen as infinite matrices acting on a discrete $\ell^2$ space via a discrete Fourier transform. Moreover, using these distribution kernels we prove that the fibre operators are toroidal pseudo-differential operators.
