Zhu Changjun

Observation of Quantum Beat in Rb by Parametric Four-Wave Mixing

Two coupled parametric four-wave-mixing processes in Rb atoms are studied using perturbation theory, which reveals clear evidence of the appearance of quantum beat at 608 cm−1, corresponding to the energy difference of the 7s−5d states of Rb atoms, in the parametric four-wave-mixing signals. A pump–probe technique is utilized to observe the quantum beat. Time-varying characteristics of the quantum beat are investigated using time-dependent Fourier transform. The results show that the time-varying characteristics of the quantum beat not only offers a sensitive detecting method for observing the decay of atomic wave packets, but also provides a potential tool for monitoring the dissociation of molecules.

Competition between Two Six-Wave Mixing Channels in Atomic Rb Vapor

Two six-wave mixing processes are achieved simultaneously in rubidium vapor and two channels are identified. Signal competition between the two channels is observed and phase matching conditions are analyzed for the two channels. The results show that the two six-wave mixing channels correspond to two parametric processes with weak coupling and, moreover, quantum interference and phase matching conditions primarily govern the signal competition.

Observation of Quantum Beating from Two Coupled Parametric Six-Wave Mixing Signals in Rb

Two processes of coupled difference-frequency axially phase-matched parametric six-wave mixing are carried out in Rb vapour by two-photon excitation using fs laser pulses, and parametric six-wave mixing signals in the infrared and near infrared regime are detected. The infrared parametric six-wave mixing signals are up-converted into the visible spectral range by sum-frequency mixing with the pump laser in a LHO3 crystal. Moreover, quantum beating at 608 cm-1, corresponding to the 7 s – 5d energy difference in Rb, is observed from the sum-frequency signal at 495 nm. As a result, we obtain modulated light signals in the visible, near infrared and infrared spectral ranges, and study the interference between 7s and 5d states of Rb.