THEORY OF QUANTUM BEAT AND POLARIZATION INTERFERENCE IN 4-WAVE-MIXING

We analyze theoretically the quantum beat and the polarization interfe rence phenomena observed as oscillations in pulsed four-wave mixing. W e show that resolution of the signal with respect to the delay between the incoming pulses as well as the detection frequency provides valua ble information on the nature of the oscillations. Most importantly, i t is very simple to distinguish between polarization interference from two independent optical transitions and quantum beats from a three-le vel system. In case of polarization interference, the phase of the osc illations shifts pi when the detected passes any of the resonances. In case of quantum beat, the phase has little dependence on the detected frequency near the resonance.