Dresden 2026 – scientific programme

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O: Fachverband Oberflächenphysik

O 37: Electronic structure theory I

O 37.2: Talk

Tuesday, March 10, 2026, 11:00–11:15, TRE/PHYS

Probing quantum coherence with free electrons — •Hebrew Crispin and Nahid Talebi — Christian-Albrechts-Universität, Kiel, Germany

Advances in ultrafast electron microscopy have enabled the study of coherent interactions between free electrons and quantum systems with high spatial resolution. Recent works have examined the coupling of free electrons to two-level systems, including the use of coherently shaped electron wavefunctions to probe coherence in individual or collective quantum emitters. Coherence can also be accessed through sequential time-resolved cathodoluminescence spectroscopy, which has demonstrated the ability to measure ultrafast radiative decay and dephasing in single emitters with femtosecond resolution. In addition, there is increasing interest in time-resolved electron energy-loss spectroscopy (EELS) techniques capable of tracking system dynamics.

Here, we present a general theoretical framework for coherent interactions between free electrons and quantum emitters prepared in arbitrary initial superposition states. We employ a fully quantum, time-dependent description of both the propagating electron wavepacket and the emitter. Quantum coherence manifests as transient oscillations in both the emitter populations and in the zero-loss peak of the spectral energy-loss probability density, even for an unmodulated electron wavepacket. Our work reveals novel coherent dynamics in the interactions between free electrons and quantum systems.

Keywords: quantum coherence; Free-electron spectroscopy; Quantum emitters; Ultrafast dynamics; Electron–matter interactions