Population transfer in a Lambda system induced by detunings

In this paper we propose a protocol to achieve coherent population transfer between two states in a three-levelatom by using two ac fields. It is based on the physics of stimulated Raman adiabatic passage (STIRAP), butit is implemented with the constraint of a reduced control, namely, one of the fields cannot be switched off. Acombination of frequency chirps is used with resonant fields, allowing us to achieve approximate destructiveinterference, despite the fact that an exact dark state does not exist. This chirped STIRAP protocol is tailored forapplications to artificial atoms, where architectures with several elementary units can be strongly coupled butwhere the possibility of switching on and off such couplings is often very limited. Demonstration of this protocolwould be a benchmark for the implementation of a class of multilevel advanced control procedures for quantumcomputation and microwave quantum photonics in artificial atoms.