Continuous propagation and energy filtering of a cold atomic beam in a long high-gradient magnetic atom guide

Abstract

We demonstrate the continuous injection and propagation of a cold atomic beam in a high-gradient (up to $2.7\phantom{\rule{0.3em}{0ex}}\mathrm{kG}∕\mathrm{cm}$) magnetic guide of $1.7\phantom{\rule{0.3em}{0ex}}\mathrm{m}$ length. Continuous injection is accomplished using a side-loading scheme that involves a sequence of two modified magneto-optic traps. Methods are developed to measure the atomic-flow temperatures and the flux under steady-state conditions. In the high-gradient portion of the guide, the guided atomic beam has a transverse temperature of $420\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{K}\ifmmode\pm\else\textpm\fi{}40\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{K}$, a longitudinal temperature of $1\phantom{\rule{0.3em}{0ex}}\mathrm{mK}$, and an average velocity of order $1\phantom{\rule{0.3em}{0ex}}\mathrm{m}∕\mathrm{s}$. Using a radio-frequency current of a fixed frequency $\ensuremath{\nu}$ coupled directly into the guide wires, atoms exceeding a transverse energy of $h\ensuremath{\nu}$ can be continuously and selectively removed from the atomic beam.