Lightwave imaging down to the scale of atoms
By exploiting the evanescent field enhancement at the apex of sharp metal tips we can create intense, localised light–matter interactions at the nanoscale. Combined with techniques like atomic force microscopy, this approach forms the foundation of an ultrafast nanoscope. To push beyond the nanoscale, we can harness strong nonlinear effects—like the quantum tunnelling of electrons — to access atomic resolution in both space and time. This opens a direct window onto atomic-scale dynamics with femtosecond precision.
This research is supported by multiple UHV microscopes: a low-temperature (base 4K) and variable temperature (base 25K) STM (Scienta Omicron), alongside a bespoke ultrafast UHV nanoscope (developed in collaboration with U. Oxford).
Subcycle Microspecroscopy
Nanoscopy directly can address light-matter interactions at their most fundamental level – yet the emergent properties of quantum materials often appear over slightly larger length scales (~1-100 µm) – especially when the energy scale of collective excitations is in the terahertz (1012) range. To access these length scales, a small aperture can be used instead of a tip to efficiently collect evanescent near fields. Doing so, we can directly address a broad range of quasiparticles – from phonon polaritons to magnons – inaccessible to conventional far-field specroscopic techniques and providing unique insight into the nonequilibrium dynamics of the quantum world.
This research is supported by multiple terahertz near-field microscopes: one based on commercial (sub)systems (Toptica and Protemics), and a bespoke ultrafast near-field aperture microscope developed in conjunction with University College London.
Moiré quantum materials
The elusive quantum states of matter hosted by two-dimensional van der Waals materials – especially when stacked and twisted to form moiré superlattices –provides an extensive platform for investigating unconventional quantum processes. Yet, measuring the dynamical processes which govern these peculiar properties can – in many cases – only be accessed with ultrafast microscopy techniques.
With a range of collaborators, we develop bespoke moiré samples for our ultrafast microscopes in-house at the quantum sandwich shop – our brand new 2D materials fabrication lab.