Observation of Reflectance Fluctuations in Metals

Through the study of the power spectra of a monochromatic light beam reflected by metallic mirrors, fluctuations in their reflectance is observed. The power spectra were obtained down to a factor $10^{-6}$ below the Standard Quantum Limit, with a dynamic range of $10^5$ in the frequency and power, using methods we developed. The properties of the spectra are investigated and their dependence on the material is analyzed. The physics underlying the phenomenon is also discussed. These fluctuations provide a new window for investigating the inner workings of materials.