Fully quantum coherent control Original Research Article

The coherent control problem is formulated in a second-quantized basis of system–field states (CC2Q). In principle, many system–field states are needed to compute the control target functional T. Here we show that a new and very simple formula for the fully quantized control functional can be obtained. As a result, T can be evaluated exactly without explicit knowledge of the system–field states. Two examples demonstrate the spirit of the approach, which can be scaled to larger problems by applying combined Lanczos and Hellman–Feynman methodologies. Although CC2Q, as a full quantum theory, does not scale as favorably as the semiclassical approach, its symmetrical treatment of system and field promises new insights because it not only views the field as a shaper of molecular coherence, but also the molecule as a shaper of field coherence.