Quantum Science of Chemical and Biological Systems

Eitan Geva, Ted Goodson, Kevin Kubarych, Jennifer Ogilvie, Roseanne Sension, Dominika Zgid, Paul Zimmerman

Summary (Prepared by Eitan Geva)

Atoms owe their existence, as well as their ability to form covalent bonds, to quantum mechanics, which makes chemistry an inherently quantum science. Indeed, molecular structure and the forces that govern molecular rearrangement are dictated by the underlying, and intrinsically quantum-mechanical, electronic structure. Furthermore, photo-induced chemical reactions (photochemistry), as well as other energy and charge transfer processes, are governed by quantum-mechanical nonadiabatic dynamics that break down the Born-Oppenheimer approximation. There are many cases where the motion of the nuclei is subject to strong quantum effects such as tunneling and zero point energy. The fact that most chemical processes of interest occur in condensed phase environments (liquid solutions, biopolymers, solid state hosts, etc.) implies that they should be treated as open quantum systems that undergo energy and quantum coherence relaxation. Indeed, correlating energy and coherence relaxation dynamics with the underlying molecular structure and chemical composition has long been a focal point of physical chemistry. A wide variety of ultrafast time resolved pump-probe spectroscopies that range from IR, through UV/vis to X-ray, and combinations thereof, provide some of the most detailed experimental probes of the quantum nature of molecular systems. Promising emerging molecular spectroscopies take advantage of quantum field-matter states (e.g. cavity-molecule polaritons) and quantum light sources (e.g. entangled two-photon absorption spectroscopy).

The UM team in this area of quantum science research combines expertise in state of the art electronic structure methods (Zgid (Green-function-based methods) and Zimmerman (wavefunction- and density-based methods)), quantum dynamics and computational spectroscopy (Geva and Zimmerman), and a wide range of nonlinear time-resolved molecular spectroscopies, including IR, UV/vis, X-ray, and combinations thereof (Goodson, Kubarych, Ogilvie, Sension), as well as spectroscopies that take advantage of the quantum nature of the radiation field (entangled two photon absorption, Goodson) and the unique properties of entangled field-matter states (molecule-cavity polaritons, Kubarych). Team members study a wide range of molecular systems, including photosynthetic reaction centers of various organisms (Ogilvie and Geva), molecular magnets (Zimmerman), strongly correlated molecular solids (Zgid), molecular polaritons (Kubarych), metal nanoclusters (Goodson), organic photovoltaic materials (Geva, Goodson, Ogilvie), and vitamin B12 (Sension and Kubarych). The research groups in this team also have a long-standing and ongoing record of fruitful collaborations among themselves as well as with other research groups from other thrusts.

Members of this team are also well positioned to make meaningful and innovative advances in the area of quantum computing. Ongoing efforts in the Zgid and Zimmerman groups are aimed toward the development of hybrid quantum-classical algorithms for electronic structure calculations, where the difficult (for classical computing) full CI component of an electronic structure calculation is off-loaded to a quantum computer, while a classical computer does the pre/post-processing. Employing electronic structure tools can also lead to rational design strategies of molecular qbits (Zimmerman).  Taking advantage of the fact that the actual dynamics of molecular systems is also subject to decoherence also suggests a strategy which shifts the emphasis from decoherence avoidance to decoherence engineering so as to mimic the decoherence of the system one is trying to simulate (Geva).