Spatiotemporal evolutions of the wavepackets |ψ′±,000(x,t)|2 from Eq. (13) with regular oscillations. Starting with a kitten state, the wavepacket pair approximately keeps their shapes and periodically oscillates. In an oscillating period, the wavepackets can go through many kitten states similar to the initial state in Fig. 1(b) and ill kitten states similar to the state at t = 2.6 in Fig. 2(b) with different distances between the wavepackets, which can be extracted by the ac field manipulations.