The Polarization Fluctuations Of A Beam In Slant Turbulent Channel

Quantum optical communication system has attracted consideration attention in quantum communication area, for its excellent features. Such as large information capacity, transmission faster and it can achieve secure information in free space. Photon polarization is one of the main carries of photon secret communication coding. So it has theoretical values to further study the degree of polarization of photon light in quantum optical communication channel propagating through turbulent atmosphere. It also can guide for designing the photon secret communication system.In this paper, we investigate the polarization fluctuations of the coherent or Gaussian-Schell quantum light propagation in the slant or horizontal atmosphere-turbulence channels. The main works of this paper are listed as follows:Firstly, the effective photon creation operator and annihilation operator of quantum light are developed which are pass through the turbulent atmosphere channel. Secondly, the Stokes operators in a turbulent atmosphere are obtained based on the effective photon creation operator and the annihilation operator. Thirdly, the expression for the degree of polarization of quantum light in a turbulent atmosphere is obtained. Finally, we use numerical simulation to analyze the properties of polarization for polarized coherent or polarized Gaussian-Schell beam propagating in turbulent atmosphere in detail. The main results are as follows:1. For the coherent and polarized light propagating through the Von Karman turbulence in a slant channel, the degree of polarization increases as the photon numbers increase and the degree of polarization declines as the atmosphere turbulent intensity increase. When the less photon numbers the changes of polarization is bigger. The photon numbers big enough the polarization tends to classic light field, it is to say the changes of polarization in turbulence can be ignored. We can also find that the changes of polarization increase as the strength of turbulence, the zenith angle of communication channel or photon beam frequency increase.2. For polarized coherent light propagating through non-Kolmogorov turbulence, the fractal constant affecting the degree of polarization of single photon beam can not be ignored. The spectral degree of polarization shows a significant increase with the fractal constantαincrease in a turbulent atmosphere. With the atmosphere turbulent intensity increase the degree of polarization declines. The degree of polarization is an increase function of coherence length. We also find that the effects of the wavelength of beam and the outer scale of turbulence on the degree of polarization for single photon beam can be ignored. The bigger zenith angles of communication and the longer inner scale of turbulence are caused the larger of the degree of polarization.3. For Gaussian Schell polarized photon beams propagating through non-Kolmogorov turbulence in a slant channel, the degree of polarization is a function of the transverse coherence width of sourceρ _s0, the source's transverse sizeω0, the power lawαof the turbulent spectrum and the zenith angle of communication channelθ. The degree of polarization increases as the source's transverse sizeω0and the power lawαincreasing for large value transverse coherent width of source (ρ _s0 > 0.01m). The degree of polarization decreases as the zenith angleθincreasing. The effects of the wavelength of beam on the degree of polarization of Gaussian Schell photon beams can be ignored. When the transverse coherent width of source is small (ρ _s0 < 0.005m), the effects of the power lawαand the zenith angleθon the degree of polarization can be ignored. The robustness of the degree of polarization of beam with wavelengthλ= 785nmis lager than that with wavelengthλ= 632.8nmandλ= 1550nm.