The transformative ability of physics and chemistry to impact quantum information science lies within the demonstration of atomic-scale control of quantum coherence, which typically involves the idea of tuning the population of multiple excited states of individual quantum systems with light. In general, the light induced physical and chemical processes lead to the dynamic reorganization of a large number of atoms and molecules. One persistent goal in the scientific community is to be able to visualize and manipulate individual molecules and compose the coherence information with the super-positions of their quantum states in real time. The combination of a femtosecond (fs) laser and a scanning tunneling microscope (STM) is believed to be the ultimate approach to achieve simultaneous spatial and temporal resolutions. The coupling of femtosecond laser pulses to the tunneling electrons breaks the diffraction limit in traditional optical microscopy and allows the detection of light-matter interaction with sub-Ångström resolution. In this colloquium, I will present the recent advancements of the Laser-STM technique to investigate the interfacial charge transfer, bond-selective photo-chemical reaction, and ultimately coherent dynamics of single molecule with joint fs-Å sensitivity.
 

Shaowei received his Ph.D. in physics from UC Irvine in 2017. Prior to that, he received his bachelor’s degree in physics from Nankai University in 2010. He is currently a postdoc fellow at Northwestern University and Heising-Simons Junior fellow at UC Berkeley. His work involves probing the physical and chemical properties of single molecules and low-dimensional materials with optical techniques and STM.