Optical analogy to quantum Fourier transform based on pseudorandom phase   ensemble
  In this paper, we introduce an optical analogy to quantum Fourier tanformation based on a pseudorandom phase ensemble. The optical analogy also brings about exponential speedup over classical Fourier tanformation. Using the analogy, we demonstrate three classcial fields to realize Fourier transform similar to three quantum particles. 
Jian Fu, Wei Fang, Yongzheng Ye
quant-ph