Discovery of an Unexpected Liquid Phase in the Periodically Driven Paul Trap

Charged particles confined in a Paul trap generally exist in one of two phases: the cloud phase - characterized by rf heating and chaotic dynamics - and the crystal phase - defined stroboscopically as a period-1 fixed point in phase space, where there is no heating. Here we present evidence supporting the existence of a liquid phase. In contrast to the cloud state, the liquid phase is characterized by an almost negligible heating rate.