With a forward cone emitting from the strong pump laser in a thermal rubidium atomic vapor, we investigate the non-degenerate parametrically amplified four-wave mixing (PA-FWM) process with dressing effects in a three-level “double-Λ” configuration both theoretically and experimentally. By seeding a weak probe field into the Stokes or anti-Stokes channel of the FWM, the gain processes are generated in the bright twin beams which are called conjugate and probe beams, respectively. However, the strong dressing effect of the pump beam will dramatically affect the gain factors both in the probe and conjugate channels, and can inevitably impose an influence on the quantum effects such as entangled degree and the quantum noise reduction between the two channels. We systematically investigate the intensity evolution of the dressed gain processes by manipulating the atomic density, the Rabi frequency and the frequency detuning. Such dressing effects are also visually evidenced by the observation of Autler-Townes splitting of the gain peaks. The investigation can contribute to the development of quantum information processing and quantum communications.

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.

Different aspects of the properties of the coexisting super-fluorescence (SFL), multi-wave mixing with the fluorescence signal in the sodium vapor are studied both theoretically and experimentally. First, by scanning the dressed-state, the properties of these coexisting processes, such as the SFL signal modulated by using the dark and bright states, the interplay between dressed-states, are observed for the first time. Then, by scanning the probe field, the interplay between the one-photon and two-photon processes of the coexisting signals is obtained with or without the external dressing fields. Such control on each process in such coexisting system has an important potential application in quantum communication.

The collisional loss rates of 63S 1/2 Rydberg atoms in cesium magneto-optical trap are measured by using the state-selective pulse field ionization technique and used to investigate the interaction between Rydberg atoms. The collisional loss rate coefficients due to collisions with Rydberg atoms and ground-state atoms are obtained by fitting the experimental data. The results indicate that the large collisional loss mainly comes from the strong long-range interaction between ultracold Rydberg atoms, and the loss rate is significantly increased under a weak electric field.

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We investigate the eight-wave mixing (EWM) process involving highly excited Rydberg states with the assistance of coexisting electromagnetically induced transparency (EIT) windows in a thermal ⁸⁵Rb vapor both theoretically and experimentally. By use of a disturbance-free optical detection method, the Rydberg EWM characterized by multiple sets of spin coherence is presented via the interplay and competition between the dressing-state effects and excitation blockade caused by strong Rydberg-Rydberg interaction. Such interplay and competition can be demonstrated by the intensity evolutions of multi-wave mixing (MWM) signals via controlling the atomic density, the frequency detuning and Rabi frequencies of corresponding laser fields. The observed Rydberg EWM tailored by EIT windows can possess of much narrower linewidth <30MHz and provide a new way for the study of Rydberg effect in the atomic ensemble above room temperature.

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 report for the first time the theoretical and experimental research on Rydberg electromagnetically induced transparency and second-order fluorescence dressing evolution by Rabi frequency control in thermal atomic vapors, in which the controlled results are well explained by the dressing effect and the Rydberg excitation blockade. Based on the certification of the Rydberg excitation blockade fraction through the dependence on principle quantum number n, we obtain dressing evolution curves, consisting of single-dressing and double-dressing in local and nonlocal blockade samples by scanning the probe and dressing fields. In addition, the competition between the Rydberg dressing second-order fluorescence and fourth-order fluorescence is first investigated. A corresponding theory is presented, which is consistent with the experimental results. Such blockade evolution regularity has potential applications in quantum control, and the Rydberg dressing may be useful for investigating multiple-body interactions, as well as for inducing short range interactions in Bose-Einstein condensates.