Ultrafast nuclear spin polarization for isotopes with large nuclear spin

Abstract

We theoretically investigate the temporal dynamics of nuclear spin induced by short laser pulses. To realize ultrafast nuclear spin polarization, we coherently excite the hyperfine manifolds and let it evolve in time. An appropriate choice of the state with large hyperfine splittings allows us to realize ultrafast nuclear spin polarization. As specific examples, we consider the various isotopes of Mg and Ca with different values of nuclear spin (1/2, 3/2, 5/2, and 7/2) and show that 89%, 76%, 49%, and 36% of nuclear spin polarization can be achieved, respectively, within a few nanoseconds, which is at least 2 to 3 orders of magnitude shorter than the time needed for any known optical methods. Because of its ultrafast nature, our scheme would be very effective not only for stable nuclei but also unstable nuclei with a lifetime as short as 1 μs.