Physics Paradigm Challenge

Mathematically speaking, you’re never going to get a crisp, stable photo of an electron's vibe; it's literally impossible.

arXiv · March 17, 2026 · 2603.15058

Florian Oberender

The Takeaway

Even as we develop lasers to manipulate single electrons with high precision, new research shows that the math required to reconstruct their full quantum identity is inherently unstable. This means that no matter how much measurement data we collect or how good our microscopes get, the resulting image will always remain blurry and prone to uncontrollable errors.

From the abstract

Recent advancements in photon induced near-field electron microscopy (PINEM) enable the preparation, coherent manipulation and characterization of free-electron quantum states. The available measurement consists of electron energy spectrograms and the goal is the reconstruction of a density matrix representing the quantum state. This requires the solution of a constrained linear inverse problem, where a positive semi-definite trace-class operator is reconstructed given its diagonal in different