Polarization fluctuations of partially coherent Hermite-Gaussian beams in a slant turbulent channel

The propagation of a partially coherent Hermite-Gaussian beam in a slant turbulent channel is studied. The analytical formula for the quantum degree of polarization of a partially coherent Hermite-Gaussian beam is derived based on the quantum Stokes operators and the generalized Huygens-Fresnel principle. It is shown that the zenith angle slightly affects the polarization degree of partially coherent Hermite-Gaussian beams, and the changes of polarization degree are affected by the coherence length, the detection photon-number and the ground refractive index structure parameter. Furthermore, the numerical simulations show that a partially coherent Hermite-Gaussian beam with bigger coherence length, higher photon-number level, lower beam order, shorter wavelength is less affected by the turbulence. These results indicate that one can choose the partially coherent Hermite-Gaussian beam with bigger coherence length, lower beam order, shorter wavelength, higher detection photon-number and set the size of transmitting aperture w(0) as about 0.065 m to improve the performance of a polarization-encoded free-space quantum communication system. (C) 2014 Elsevier GmbH. All rights reserved.