Raman transitions between hyperfine clock states in a magnetic trap

TL;DR

This study explores Raman transitions between hyperfine clock states in a $^{87}$Rb atom chip trap, highlighting interference effects, light shift sensitivities, and potential decoherence sources.

Contribution

It provides a detailed experimental analysis of Raman transitions in a magnetic trap, including interference effects, light shift optimization, and dynamic modeling with master equations.

Findings

Transition frequency is highly sensitive to laser intensity ratio.

Optimal intensity ratio reduces differential light shifts and narrows linewidth.

Good agreement between experimental data and master equation model.

Abstract

We present our experimental investigation of an optical Raman transition between the magnetic clock states of $^{87}$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 multi-level structure of $^{87}$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.