We can increasingly drive quantum materials into new states with ultrafast light – but we still rarely watch these transformations unfold simultaneously in real time and real space, down to the atomic scale. Resolving ultrafast light-driven dynamics where new electronic and structural properties – and ultimately functionality – emerge remains a fundamental challenge.
In this talk, I will show how this ambitious goal can be achieved with our recent developments in lightwave microscopy. I will present the ultrafast scanning tunnelling spectroscopy utilizing lightwave-driven currents to take snapshots of the electronic spectrum of an atomic vacancy faster than its vibration period [1]. I will further show NOTE – a fundamentally new near-field optical tunnelling emission approach that exploits extreme nonlinearities in near-fields to bring all-optical microscopy to the atomic scale [2, 3] while retaining subcycle temporal information about light [2]. I will demonstrate how we use these techniques to elucidate the ultrafast nanoscale dynamics leading to the formation of metastable quantum states in 1T-TaS2.
[1] C. Roelcke, YG et al., Nat. Photon. 18, 595–602 (2024).
[2] T. Siday, YG et al., Nature 629, 329–334 (2024).
[3] F. Schiegl, YG et a., Nano Lett. 26, 1689–1696 (2026).