  We present a well-tailored sequence of two Gaussian-pulsed drives that
achieves perfect population transfer in STImulated Raman Adiabatic Passage
(STIRAP). We give a theoretical analysis of the optimal truncation and relative
placement of the Stokes and pump pulses. Further, we obtain the power and the
duration of the protocol for a given pulse width. Importantly, the duration of
the protocol required to attain a desired value of fidelity depends only
logarithmically on the infidelity. Subject to optimal truncation of the drives
and with reference to the point of fastest transfer, we obtain a new
adiabaticity criteria, which is remarkably simple and effective.

Quantum Physics