Donor and defect electronic spins in solids are promising platforms for quantum technologies. Understanding how systems such as donors in silicon or defects in diamond and silicon carbide decohere under different experimental conditions is key to enabling improved materials design and to identifying optimal operating conditions.   In this talk I will describe two recent sets of experiments from our group.  In the first set of experiments we measure the decay of Hahn-echoes to characterize the spectral diffusion of electron spins in phosphorus-doped silicon at high magnetic fields (~8T) and show how this can be modulated using optical excitation.  In the second series of experiments we compare the coherence times of ensembles of substitutional nitrogen (P1) centers and optically-polarized nitrogen-vacancy (N centers in diamond at lower magnetic fields using CPMG dynamical decoupling sequences.

Biography:

 Professor Ramanathan is an experimental physicist working at the interface of quantum information processing and condensed matter physics. He has a B. Tech. degree in Electrical Engineering from the Indian Institute of Technology, Bombay, an M.S. in Biomedical Engineering from the University of North Carolina at Chapel Hill, an S.M. in Technology and Policy and an Sc.D. in Nuclear Engineering from the Massachusetts Institute of Technology. Following postdoctoral training at Harvard Medical School, Nottingham University and MIT, he spent a number of years at MIT as a Research Scientist. He joined Dartmouth College in August 2010.