The experiments use independent time-varying voltages on a set of electrodes to move a trapping potential well (and the ion in contains) along a path.
They need high-quality voltage waveforms on those electrodes to make sure they don't lose the ion or disturb its quantum state, and the DACs they had in '10 didn't have the update rates of the FPGA apparatus they built in '12 and they improved transport times by something like a factor of 100 by making the switch.
