Liwen Ko

(1) Quantum light spectroscopy. Spectroscopic techniques using classical laser light have been used extensively to study the energy transfer dynamics of photosynthetic light harvesting complexes in vitro, resulting in many insights. However, the spectra obtained for light harvesting complexes are often highly congested due to the large number of pigment molecules. New techniques such as the two-dimensional electronic-vibrational (2DEV) spectroscopy have been able to resolve some spectral congestions. Another potential way to resolve spectral congestion is quantum light spectroscopy, where one exploits non-classical properties of light (such as frequency-entanglement and non-classical photon correlations) to try to access information that is not accessible through classical spectroscopy. Liwen investigates how quantum light can be used to provide an advantage over classical spectroscopy. He has also developed quantum-inspired classical spectroscopy experiments, and he is studying the potential benefits of these experiments.

(2) Nuclear vibration effects in electronic dynamics. Nuclear motion is known to play an important role in the efficient energy transfer and charge transfer dynamics in photosynthesis. A detailed understanding of the microscopic mechanism of the energy and charge transfer dynamics, including the role of nuclear motions, will provide insights into the design of artificial photosynthetic systems. Liwen uses open quantum systems methods (such as the hierarchical equations of motion (HEOM) or the simpler Lindblad dynamics) to study how nuclear motions influence the electronic dynamics. Working with the time-resolved x-ray diffraction experiments performed in Jan Kern's group (LBNL), he is now trying to combine these open quantum systems methods with molecular dynamics simulations and quantum chemistry calculations to identify the nuclear motions that follow the initial light excitation.