Quantum state engineering in ion-traps via adiabatic passage

We propose two relatively robust schemes to generate entangled W states of three (or generally N) ions in ion trap systems by using adiabatic passage technique and appropriately designed ion-field couplings in a single step. In the first scheme, we apply the N-pod fractional stimulated Raman adiabatic passage (F-STIRAP) technique to generate W state of N ions using two Gaussian laser pulses. We also show that the W state of N − 1 ions can be created via a simple N-pod standard STIRAP by two laser pulses. In the second scheme, we generate the entangled state of N ions via π-pulse technique by a single laser pulse. We also study the population transfer of the system by numerical solutions of the master equation, considering the effect of decoherence channels due to laser intensity fluctuations and dissipation in the phonon modes