GENERATION AND DETECTION OF NONCLASSICAL FIELD STATES BY CONDITIONAL MEASUREMENTS FOLLOWING 2-PHOTON RESONANT INTERACTIONS

A simple scheme is presented that allows the generation and detection of nonclassical states of the electromagnetic (em) field with controll able (predetermined) photon-number and phase distributions. It is base d on the two-photon resonant interaction of a single em field mode in a high-e cavity with initially excited atoms crossing the cavity seque ntially (one at a time). The sequence duration should be much shorter than the cavity-mode lifetime. Nonclassical states of the field are ge nerated conditionally, by selecting only those sequences wherein each atom is measured to be in the excited state after the interaction. The field distribution resulting from a sequence of N such measurements i s peaked about 2N positions in the phase plane, which evolve:sinusoida lly as a function of the atomic transit times and are therefore simply controlled. When these peaks are chosen not to overlap, the field sta te constitutes a generalized Schrodinger cat. By choosing them to over lap, we can make parts of the field distribution strongly interfere, g iving rise to decimation of the photon-number distribution. In particu lar, this process can prepare Pock states with controlled photon numbe rs. The generated phase distribution can be detected by monitoring the pattern of revivals in the excitation of a ''probe'' atom.