TRANSIENT 2-ION CHAOS

Transient orderchaos transitions of two Ba+ ions are observed where the duration of the chaotic state increases smoothly with an increasing Mathieu control parameter q. The transient regime precedes the transition point qc for stationary chaos, which is well defined and reproducible. The perturbative step that initiates chaos takes place on a time scale of 1 min, far longer than previous estimates, and is due to a single H2-Ba+ collision (H2 pressure 5×10-11 Torr). In contrast to random collision events, chaos can be initiated deterministically by a new pulse technique. These observations resolve earlier anomalies and challenge computer simulations. © 1990 The American Physical Society.