Calderón problem for systems via complex parallel transport
Mihajlo Cekić
TL;DR
This work advances the Calderón problem for systems by proving uniqueness of a connection $A$ and potential $Q$ on a compact manifold with boundary under a CTA-type embedding into $\mathbb{R}^2 \times M_0$, up to natural gauge. The authors introduce and study the complex ray transform and the complex parallel transport, developing a leafwise Del Bar framework and CGO solutions that reduce the inverse problem to a complex transport problem on a 2-frame leaf bundle $L$. By leveraging limiting Carleman weights, transport reductions, and Gaussian beam techniques, they obtain reconstruction results in both simple and arbitrary transversal geometries, including non-unitary connections and non-skew-Hermitian potentials. The approach uncovers a deep link between complexified geometric optics, transport tomography on leaf spaces, and gauge-invariant recovery, with potential extensions to Lorentzian settings and broader regularity regimes.
Abstract
We consider the Calderón problem for systems with unknown zeroth and first order terms, and improve on previously known results. More precisely, let $(M, g)$ be a compact Riemannian manifold with boundary, let $A$ be a connection matrix on $E = M \times \mathbb{C}^r$ and let $Q$ be a matrix potential. Let $Λ_{A, Q}$ be the Dirichlet-to-Neumann map of the associated connection Laplacian with a potential. Under the assumption that $(M, g)$ is isometrically contained in the interior of $(\mathbb{R}^2 \times M_0, c(e \oplus g_0))$, where $(M_0, g_0)$ is an arbitrary compact Riemannian manifold with boundary, $e$ is the Euclidean metric on $\mathbb{R}^2$, and $c > 0$, we show that $Λ_{A, Q}$ uniquely determines $(A, Q)$ up to natural gauge invariances. Moreover, we introduce new concepts of complex ray transform and complex parallel transport problem, and study their fundamental properties and relations to the Calderón problem.
