arXiv:1012.2156 · Physical Review A
Elimination of the degenerate trajectory of a single atom strongly coupled to a tilted TEM 10 cavity mode
Pengfei Zhang, Yanqiang Guo, Zhuoheng Li, Yuchi Zhang, Yanfeng Zhang, Jinjin Du, Gang Li, Junmin Wang, Tiancai Zhang
Abstract
We demonstrate the trajectory measurement of the single neutral atoms deterministically using a high-finesse optical microcavity. The single atom strongly couples to the high-order transverse vacuum TEM${}_{10}$ mode, instead of the usual TEM${}_{00}$ mode, and the parameters of the system are $({g}_{10},\ensuremath{\kappa},\ensuremath{\gamma})=2\ensuremath{\pi}\ifmmode\times\else\texttimes\fi{}(20.5,2.6,2.6) \text{MHz}$. The atoms simply fall down freely from the magneto-optical trap into the cavity modes, and the trajectories of the single atoms are linear. The transmission spectra of atoms passing through the TEM${}_{10}$ mode are detected by single-photon counting modules and are well fitted. Thanks to the tilted cavity transverse TEM${}_{10}$ mode, which is inclined to the vertical direction $~$${45}^{\ifmmode^\circ\else\textdegree\fi{}}$, it helps us to eliminate the degenerate trajectory of the single atom falling through the cavity and to obtain a unique atom trajectory. An atom position with a high precision of $0.1 \ensuremath{\mu}\text{m}$ in the off-axis direction (axis $y$) is obtained, and a spatial resolution of $5.6 \ensuremath{\mu}\text{m}$ is achieved in a time interval of $10 \ensuremath{\mu}\text{s}$ along the vertical direction (axis $x$). The average velocity of the atoms is also measured from the atom transits, which determines independently the temperature of the atoms in a magneto-optical trap, $186\ifmmode\pm\else\textpm\fi{}19 \ensuremath{\mu}\text{K}$.