Prof Niek van Hulst (ICFO Barcelona) is visiting the UCL Physics Department today and giving the annual Harrie Massey Lecture on the topic of Coherent control of single molecules, complexes and nanoantennae.
Abstract: The observation of quantum mechanical effects in biological systems, such as light-harvesting antennae, has opened a lively debate as to the role of coherences in natural systems. Traditionally, such coherences are probed by manipulating quantum interference effects with shaped laser pulses. Yet the intrinsic structural inhomogeneity and environmental fluctuations of complex systems at ambient conditions average out most oscillatory spectroscopic features. Only by “single molecule detection” one can hope to catch a glimpse through the disorder. This lecture will present coherent control of single molecules, allowing both observation and manipulation of vibrational wave-packet interference and Rabi-oscillations in individual molecules at ambient conditions. The single-molecule approach ensures that the ultimate degree of coherent control can be realized. We have applied our novel method to single light-harvesting complexes and optical nanoantennas. Recent results on ultrafast quantum coherent energy transfer and femtosecond control of nanoscale hotspots will be presented.