We demonstrate controllable excitation of the center-of-mass longitudinal motion of a
thermal antiproton plasma using a swept-frequency autoresonant drive. When the plasma is
cold, dense, and highly collective in nature, we observe that the entire system behaves as a
single-particle nonlinear oscillator, as predicted by a recent theory. In contrast, only a
fraction of the antiprotons in a warm plasma can be similarly excited. Antihydrogen was
produced and trapped by using this technique to drive antiprotons into a positron plasma …

We will present results of the first longitudinal autoresonant excitation of a thermal antiproton
plasma. We apply a swept-frequency drive field to an antiproton plasma in an anharmonic
potential to resonantly control the longitudinal energy of the particles in the potential. We
observe autoresonant excitation of the plasma as a macroparticle in the regime of cold,
dense plasmas, while warmer, tenuous plasmas are not excited completely (as predicted by
theory [1]). This technique has been used for initiating the formation of antihydrogen, as it …