For the first time, we study the parametric amplification process of multi-wave mixing (PA-MWM) signal and cascaded-nonlinearity process (CNP) in sodium vapors both theoretically and experimentally, based on a conventional phase-conjugate MWM and a self-diffraction four-wave mixing (SD-FWM) processes, which are pumped by laser or amplified spontaneous emission (ASE), respectively. For laser pumping case, SD-FWM process serves as a quantum linear amplifier (a CNP) out (inside) of the resonant absorption region. While for ASE case, only the CNP occurs and the output linewidth is much narrower than that of the MWM signal due to the second selected effect of its electromagnetically induced transparency window. In addition, the phase-sensitive amplifying process seeded by two MWM processes is discussed for the first time. Theoretical fittings agree well with the experiment. The investigations have important potential applications in quantum communication.

We study the enhancement and suppression of different multi-waving mixing (MWM) processes in a Rydberg-EIT rubidium vapor system both theoretically and experimentally. The nonlinear dispersion property of hot rubidium atoms is modulated by the Rydberg-Rydberg interaction, which can result in a nonlinear phase shift of the relative phase between dark and bright states. Such Rydberg-induced nonlinear phase shift can be quantitatively estimated by the lineshape asymmetry in the enhancedand suppressed MWM processes, which can also demonstrate the cooperative atom-light interaction caused by Rydberg blockaded regime. Current study on phase shift is applicable to phase-sensitive detection and the study of strong Rydberg-Rydberg interaction.

In this letter, we show polarized dressing suppression and enhancement of six-wave mixing involving Rydberg in a multi-Zeeman-level atomic system. By scanning the frequency detuning of the dressing field, we observe the suppression and enhancement of Rydberg six-wave mixing with different polarization of the probe field in thermal vapors. Since different polarization states of the dressing field can select different transitions among multi-Zeeman levels, the polarization dependence of Rydberg dressing is investigated for the first time. Theoretical calculations are given and are in good agreement with the experimental results.

We investigate a novel detection technique to study the coherent control of dressed multiwave mixing (MWM) process. A stable laser dressing field with a wavelength of 480 nm is realized via the second harmonic generation technique. By scanning such dressing field, stable Rydberg MWM signals with high signal-to-noise ratio are observed. With the MWM signals oscillated in a stabilized three-mirror cavity and cavity dressing field scanned, dressed MWM cavity modes are obtained. Thanks to the stable 480 nm and cavity dressing fields, the longterm drift of dressed MWM in cavity can be dramatically reduced to <4 MHz from 100 MHz.

We investigate fluorescence (FL) and spontaneous parametric four-wave mixing (SP-FWM) signals in V-, Λ- and N-type energy level systems by changing the frequency detuning or power of the dressing field in Pr3+ doped Y2SiO5 at 77 K. The lifetime of the two kinds of signals has been calculated, and the desired experimental results have been obtained. We successfully control the intensity and lifetime of fluorescence and SP-FWM signals by changing the power or frequency detuning of the dressing field. The research has potential applications in optical switches and all optical communication.