arXiv:1605.05230 · Physical Review A
Raman transitions between hyperfine clock states in a magnetic trap
Julian B. Naber, Lara Torralbo-Campo, T. Hubert, R. J. C. Spreeuw
Abstract
We present our experimental investigation of an optical Raman transition between the magnetic clock states of $^{87}\mathrm{Rb}$ in an atom chip magnetic trap. The transfer of atomic population is induced by a pair of diode lasers which couple the two clock states off-resonantly to an intermediate state manifold. This transition is subject to destructive interference of two excitation paths, which leads to a reduction of the effective two-photon Rabi frequency. Furthermore, we find that the transition frequency is highly sensitive to the intensity ratio of the diode lasers. Our results are well described in terms of light shifts in the multilevel structure of $^{87}\mathrm{Rb}$. The differential light shifts vanish at an optimal intensity ratio, which we observe as a narrowing of the transition linewidth. We also observe the temporal dynamics of the population transfer and find good agreement with a model based on the system's master equation and a Gaussian laser beam profile. Finally, we identify several sources of decoherence in our system, and discuss possible improvements.