Physical Review Letters
The control-theoretical analysis of control of trapped-ion quantum states is described with optical pulses in large Hilbert spaces. The resonant bichromatic fields were applied to completely uncontrollable and controllable systems. The specific temporal shapes of control fields are important to determine controllability of trapped system. The Hilbert space of qubit-harmonic oscillator is made finite and Schrödinger equation controllable through resonant bichromatic fields.
Rangan, Chitra; Bloch, A.M.; Monroe, C.; and Bucksbaum, P.H.. (2004). Control of Trapped-Ion Quantum States with Optical Pulses. Physical Review Letters, 92 (11), 113004-1-113004-4.