DEGREE OF DEPOLARIZATION OF QUANTIZATION HERMITE-GAUSSIAN BEAM IN A TURBULENT ATMOSPHERE

Abstract

Based on quantum Stokes operators and non-Kolmogorov spectrum model of index-of-refraction ∞uctuation, the analytical for- mulas for the quantum degree of depolarization of quantization Hermite-Gaussian (QHG) beams propagating in a turbulent atmo- sphere slant channel are derived. The nonclassical polarization prop- erties of QHG beams propagating in turbulent atmosphere are stud- ied numerically. It is found that the polarization ∞uctuations of QHG beams are dependent of the turbulence factors such as spectrum power- law exponent, refractive index structure parameter at the ground and zenith angle. The degree of depolarization of QHG beams has a salta- tion and reaches the minimum value at spectrum power-law exponent fi = 11=3, the refractive index structure parameter at the ground of the turbulent atmosphere slightly afiects the polarization degree of QHG beams which have travelled a long distance, and the change of polariza- tion degree decreases with the increasing zenith angle. Furthermore, the numerical simulations show that QHG beams with higher photon- number level, lower beam order, shorter wavelength are less afiected by the turbulence. These results indicate that One can choose low-order QHG beams with wavelength ‚ = 690nm as optical carrier, increase photon number, set the size of transmitting aperture w0 as about 0.1m, and detect communication signals at the central region of beams to im- prove the performance of a polarization-encoded free-space quantum communication system.