The Investigation Of Quantum Correlation And Optical Photonic Structure In Cesium Atomic Ensemble

Quantum correlation is the most important component in the quantum communication.It has an incomparable superiority than classical information in ensuring the safety of information, increasing the information capacity, and so on. However, to realize the long-distance quantum communications, we must resort to the quantum repeater basing on the quantum storages. Hence, the related quantum correlation preparations, manipulations and applications with the wavelength atomic absorption lines and optical communications window are the highlighting researches in quantum communication domain. The methods we have studied for many years in preparation of correlation, and entangled light which are the optical parametric down conversion and frequency doubling processes. The prepared entangled light hardly match with the atomic absorption lines, and hardly realize the necessary continuously tunable which interact with atom. So it is very significant for the atomic medium to directly prepared with the quantum correlations and entanglements. This article will be central on the preparation of atomic vapor, and research the bright twin beans in atomic vapor thickness, the nonlinearity in atomic vapor and phonic crystal effect in atomic vapor, mainly include the following four parts: The first chapter is an introduction. Many physical processes are completed by the atomic coherence effect, like slowing light, light storage, and so on. So in this chapter we will first briefly describe the effect of electromagnetically induced transparency, and then focus on the effect of electromagnetically induced grating which is another nonlinear interaction between atoms and light.In the second chapter, the optical thickness is an important parameter in the international process between atoms and light, premise in meeting the transition selection rules, use the Bloch equation which interact the light and simple two level atomic system, can we popularize the equation to the real atomic system. At last, we accurate simulation the transmission curves when the light at different intensity and polarizations through the atom vapor at different temperatures, and calculated the optical thickness of the atomic vapor. It is proved that optical thickness has a relationship with the intensity and polarization of the light and the temperature of the atomic vapor. When the light intensity is larger, the optical thickness get smaller, and the temperature of the atomic vapor becomes higher, the optical thickness get larger.In the third chapter, we research on the cesium as Raman four wave mixing, we also measure and analyze the intensity-difference noise between the probe and the conjugated field under different lengths of the atomic vapor and different intensities of the pump light. We theoretically establish an effective Hamiltonian system, which depends on the specific atomic parameter. Based on the beam splitter model, we analyze the optical losses after squeezing. Theoretical calculate the gain and the noise reduction of different atoms at the same parameters, and reveal the difficulties of obtain a large noise reduction in the Cesium atomic vapor.In the fourth chapter, we theoretically investigate the absorption properties of the electromagnetically induced transparency medium coupled by standing wave field. Experimentally measure the transmission properties of probe light, and find that the transmission curve which is similar to the photonic band gap of photonic crystals. Periodic spatial intensity distribution of the standing wave field will make the refractive index of the medium be a periodic spatial modulation, which is also analogous to a photonic crystal. At last, we can conveniently manipulate the center frequency location of the photonic bandgap by adjusting the relative frequency detuning of the two beams of formed the standing wave. This is more convenient than doping the photonic crystal to change the photonic bandgap properties.The innovative works are:I. This experiment research on the cesium cell in different intensities and polarizations has corresponding optical thickness under the influence of different energy levels and temperatures. This provides a good method for the accurate standardized cesium atom vapor’s optical thickness under high temperatures.Ⅱ.Using the Raman four-wave mixing produced high-frequency difference bright-twin beams in cesium atoms, we theoretically established an effective Hamiltonian which depends on the specific atomic, reveal the difficulties of obtaining a large quantum correlations in a cesium atomic vapor.Ⅲ. By the strong absorption property of EIT medium coupled by standing wave, can we realize the photonic band gap properties of photonic crystals. Meanwhile, can we achieve the manipulation to the center frequency location of the photonic band gap by adjusting the relative frequency detuning of the two beams which form the standing wave.