Attosecond space-time imaging of coherent quantum dynamics

ended

Coherence is a fundamental property of quantum mechanics, characterizing phase correlations of light or matter waves. It is at the heart of many physical phenomena, such as the creation of electron-hole pairs in the photovoltaic effect or the fast migration of electronic charge within a molecule. In order to study coherent electron dynamics, extremely high spatial and temporal resolving power is required, which is highly challenging. Well-established imaging methods like scanning tunneling microscopy achieve atomic-scale spatial resolution, while lacking ultrafast time resolution. At the temporal frontier, I recently bridged the gap between attosecond spectroscopy (1as = 10-18 s) and the nano-scale. The goal of my research program is to unlock the full potential of attosecond spectroscopy by achieving simultaneous spatial and temporal probing of ultrafast coherent phenomena. The proposed approach relies on the introduction of attosecond spectroscopy into scanning tunneling microscopy and electron holography. The spatial resolution of these methods is based on nano-scale needle tips, serving as local probes or as point-like electron sources. My team and I will develop attosecond temporal gates at the tips, enabling pump-probe spectroscopy. The resulting “pump” – triggering the coherent dynamics – and the “probe” – measuring its evolution – are localized in space and time, with attosecond and sub-nanometer precision. This combination will allow watching charge dynamics in a single molecule and observing multi-electron dynamics in nanostructures with atomic-scale site selectivity, as they evolve in real time. My approach has the potential to shed new light on quantum optics, plasmonics, molecular electronics, surface science and femtochemistry. In particular, my team and I will study quantum tunneling on the atomic level, charge migration in organic molecules and electron-hole dynamics in low-dimensional solid-state systems.