Remote spectral measurement using entangled photons
  By utilizing the frequency anticorrelation of two-photon states produced via spontaneous parametric down conversion (SPDC), the working principle of a novel remote spectrometer is demonstrated. With the help of a local scanning monochromator, the spectral transmission function of an optical element (or atmosphere) at remote locations can be characterized for wide range of wavelengths with expected high resolution. 
Giuliano Scarcelli, Alejandra Valencia, Samuel Gompers, and Yanhua   Shih