Abstract
We propose a method for transferring atoms to a target quantum state for a multilevel quantum system with sequentially increasing, but otherwise unknown, energy splitting. This is achieved with a feedback algorithm that processes off-resonant optical measurements of state populations during adiabatic rapid passage in real-time. Specifically, we reliably perform the transfer |F=2,m_F=2 → |1,1 → |2,1 for a sample of ultracold ⁸⁷Rb in the presence of a random external magnetic field.