4D Scanning Tunneling Microscopy
Achieving atomic scale resolution both in space and time is one of the fundamental pursuits in modern science. Pump-probe measurements with ultrashort pulses have now gone down to tracking electronic motion in atoms with few hundreds of attosecond resolution, but nevertheless suffer dramatically on spatial resolution, which is only few microns hence limiting the capability to probe an individual microscopic entity. To overcome this fundamental barrier we are integrating two state-of-the art techniques, scanning tunneling microscopy and attosecond technology. In our ultrafast STM experimental setups, laser pulses lasting only few femtoseconds (~ 6 fs) are coupled into the STM. The laser produces tailored field-reproducible waveforms (carrier-envelope phase stable) with sub-cycle precision and tunability. The capability to precisely vary the phase of our laser pulses gives us a temporal resolution of ~ 200 attoseconds. Field-induced control over electron dynamics in driven quantum systems is achieved by taming the phase of the laser pulses. Our experimental approach allows us to achieve the ultimate spatio-temporal resolution to resolve dynamics in microcosm i.e. attosecond- Ångström scale resolution. Part of this experimental development is done in collaboration with the group of Prof. Leitenstorfer at Konstanz University.