Quantum polarization fluctuations of a partially coherent Laguerre–Gaussian beam in a slant turbulent channel

Abstract

The propagation of a partially coherent Laguerre–Gaussian beam in a slant turbulent channel is studied. The analytical formula for the quantum degree of polarization of a partially coherent Laguerre–Gaussian beam is derived based on the quantum Stokes operators and the extended Huygens–Fresnel principle. It is shown that the zenith angle slightly affects the polarization degree of partially coherent Laguerre–Gaussian beams, and the changes of polarization degree are affected by the detection photon-number. Furthermore, the numerical simulations show that a partially coherent Laguerre–Gaussian beam with higher photon-number level, lower beam orders, longer wavelength is less affected by the turbulence. These results indicate that one can choose the partially coherent Laguerre–Gaussian beam with lower beam orders, longer wavelength, higher detection photon-number to improve the performance of a polarization-encoded free-space quantum communication system.