Our paper on contrasting quantum decoherence and classical noise model is published in J. Chem. Phys. Quantum decoherence can be understood in several pictures. The most rigorous one being the system-bath model. In it, the bath is treated quantum mechanically and decoherence arises due to the system-bath entanglement generated by their interaction. A much simpler picture is the classical noise model whereby the effects of bath is to introduce a time-dependent stochastic term into the system. As such, decoherence appears from a statistical average of the stochastic but unitary dynamics. The intriguing question is whether the simple intuitive classical noise picture can reproduce the decoherence dynamics in a full quantum model. In this paper, we develop general criteria for the classical model to mimic quantum decoherence.

Our paper on the optical properties of laser-driven matter is published in Phys. Rev. A. In this work, we develop a theory of optical absorption that is valid for non-equilibrium systems, in particular, laser-driven systems. We applied this theory to investigate the emergent optical absorption properties of a nanoscale semiconductor driven by a intense non-resonant light. It turns out that the optical absorption properties of a laser-driven matter is qualitatively different from the pristine material. Depending on the strength of the dressing light, it can generates replicas of absorption bands that are separated by integer number of photon energies, and generates absorption/emission signals at THz regime.

Theoretical chemists think light as semiclassical in the sense that the quantum nature of light is not affecting chemistry. Technically speaking, the light field comes into play in the basic equation to describe chemistry, time-dependent Schodinger equation, as an external time-dependent parameters. However, light is quantum mechanical in nature. And with the advent of nonclassical light realized in labrarotory, it is essential to go beyond the semiclassical view and take a full quantum mechanical treatment of light. 

If you are interested in a deep understanding of light, the book “Quantum Optics” by Scully and Zubairy is an excellent book that gives a comprehensive introduction to the quantum mechanical properties of light. The prerequisite, in my opinion, is familiarity with basic quantum mechanics. 

I officially start my postdoc position at the University of California, Irvine working with Prof. Shaul Mukamel. I will work on manipulating and controlling chemistry by optical cavities.

Our paper on the relationship between electronic interaction and electronic decoherence is published in J. Chem. Phys. In it, we showed that the electronic interactions do not affect electronic decoherence in the pure-dephasing limit, that is when the electronic transitions between the diabatic states are not significant. 

The book “Nonlinear optics” by Robert W. Boyd is excellent. One can find essentially everything about nonlinear optics in this book. While this book is not written particularly for chemists (as the nonlinear media is not always consist of molecules), majority of the concepts and treatments are beneficial to chemists. The treatment is a combination of quantum mechanics for matter and Maxwell equations for light. The chemists intended to focus on how light changes matter without considering the change of light (the light acts as a parameter in the equations of motion for matter).  But matter also changes light, and we have to combine both views to have a complete picture of laser-matter interaction.

Since I am going to join Prof. Shaul Mukamel group soon, I recently read his book  “Principles of nonlinear optical spectroscopy” again. This is an excellent book for nonlinear spectroscopy in molecules. Although I do think it is a little bit technical in the sense that it goes into the third-order dipole response functions w.r.t. the external electric field. But after getting some familiarity with the mathematical language (i.e. Liouville space pathways), it becomes a wonderful reading experience.