Producing ultracold and trappable antihydrogen atoms

Abstract

Both experiments and simulations have shown that the temperature of antihydrogen atoms $(\overline{\mathrm{H}})$ formed in a strongly magnetized positron-antiproton plasma is mainly determined by the heavy particles' temperature. A routine to keep cooling antiprotons $(\overline{p})$ by using ultracold $(<1\phantom{\rule{0.3em}{0ex}}\mathrm{K})$ electrons is proposed under attainable experimental conditions. When cold positrons are loaded into such a low-temperature electron-antiproton mixture, ultracold antihydrogen atoms can be produced at a temperature below $\ensuremath{\sim}1\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. Our large-scale molecular-dynamics simulations, which involve $20\phantom{\rule{0.2em}{0ex}}000$ particles (${e}^{\ensuremath{-}}$, ${e}^{+}$, and $\overline{p}$) evolving up to $1\phantom{\rule{0.3em}{0ex}}\mathrm{\ensuremath{\mu}}\mathrm{s}$, have confirmed the generation of trappable $\overline{\mathrm{H}}$ atoms.