Two-stage Rydberg charge exchange: An efficient method for production of antihydrogen

An efficient method for production of cold antihydrogen $\left(\mathrm{H}¯\right)$ is proposed. Alkali-metal atoms laser excited to a Rydberg state are charge exchanged with cold trapped positrons, producing Rydberg states of positronium. In a second Rydberg-state charge exchange, the positronium atoms give up their Rydberg positrons to cold trapped antiprotons, producing Rydberg states of $\mathrm{H}¯$. These $\mathrm{H}¯$ atoms soon decay down to the ground state, and, because they are cold, could be trapped in a magnetic trap. The efficiency of the process results from the extremely large cross sections for Rydberg charge exchange. Classical trajectory Monte Carlo calculations indicate an $\mathrm{H}¯$ instantaneous production rate of 10${}^6/$s.