Generation Of The Squeezing State Of The Light In Four Wave Mixing In Thermal Atom

Light field is a kind of quantum field, therefore there are some natural quantum char-acteristics. These can not be explained by classical optical theory, we call them non-classical characteristics. Now there are there non-classical characteristics in the ex-periment, they are photonic anti-bunching, poisson distribution and squeezed state. Re-search of the non-classical effect of quantum light field not only help further reveal the quantum nature of light field, and these effects can also have important application in op-tical communication, high precision interference measuring and weak signal measurement and so on.Since non-classical state was realized in experiment, it has been used in various fields, especially the application in the quantum information. Such as quantum non-demolition measurement, quantum teleportation, quantum secret communication and quantum dense coding and so on. We mainly study the squeezed state of optical fields which are important resources of quantum information processing. In recent years, people begin to pay much attention to research of squeezed state, and have made a lot of progress. The United States’s Bell LABS first observed the squeezed state in experiment in1985. They use non-degenerate four wave mixing device of sodium atom beams. Later in the experiment people use fiber of100meters was pumped by argon laser as the medium of non-degenerate four wave mixing to observe the squeezed state. So people are beginning to pay more attention to four wave frequency mixing process, especially the experiment of using non-degenerate four wave mixing process to produce bright twin beams with strong frequency correlation in the atomic gas, it has become a hotspot in the quantum optics field. Four wave mixing is a non-linear interaction between light and matter that permits the transfer of energy and momentum between four modes of the electric field via intera-tion with a medium. Typically, a high intensity pump laser is used to induce a strong non-linear polarization in the medium, which then causes the medium to interact with other field modes.In this thesis, we mainly study the generation of intensity difference squeezed state by non-degenerate four wave mixing process in the medium of Rb atomic steam, the main content consists of the following parts: Firstly, a brief description of the theoretical knowledge of four wave mixing process in Rb atomic medium, the generation of intensity difference squeezed state by non-degenerate four wave mixing process, phase matching, gain of the process, and the detection system.Secondly, according to the theory analysis, we build the experimental platform, adjust the light path in experiment, realize the four wave mixing process in the Rb atomic to pro-duce intensity difference squeezed state, and detect it by the experimental detection sys-tem, according to the detection results, choose appropriate experimental device and ex-perimental parameters to improve the squeezed degree.Finally, in order to enable the laser frequency to be long time in the stable frequency we need, we phase locked a laser to the other laser by the signal of beat frequency between two lasers, based on the instrument:Source locking CW microwave frequency counter. This work enables us to investigate the electromagnetically induced transparency spec-troscopy, Raman spectroscopy and four wave mixing in atomic system.