Dear Group, On Monday at 2pm in the Division Room Dr. Gian Giacomo Guerreschi, a postdoc candidate visiting our group, will be presenting a special group meeting. His abstract is given below. Quantum and classical control of radical pair reactions in solution ======================= The yield of chemical reactions involving intermediate radical pair is influenced by magnetic fields well beyond the levels expected from energy considerations. This dependence can be traced back to the microscopic dynamics of electron spins and constitutes the basis of the chemical compass. In addition, the radical-pair mechanism is one of the two main hypotheses to explain the navigability of animals in weak magnetic fields, enabling, e.g., birds to see Earth's magnetic field. Here, we study the role of radical-pair entanglement in this mechanism and show how quantum control can be used to either enhance or reduce the performance of a chemical compass. Furthermore, we propose a new experimental approach based on molecular photoswitches to achieve control on the kinetics of the chemical reaction and to allow short-time resolution of the spin dynamics. Our proposals enable experiments to test some of the standard assumptions of the radical pair model and improve the sensitivity of chemical magnetometers by two orders of magnitude. -- Ryan Babbush | PhD Student in Chemistry (949) 331-3943 | babbush(a)fas.harvard.edu Harvard University | Aspuru-Guzik Research Group 12 Oxford Street, Box 400 | Cambridge, MA 02138