[Legacy Report] The Magic of Correlation Measurements

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The presentation focuses on the correlation (cross-spectrum) experimental method and on its applications. The noise of a device under test (DUT) is measured simultaneously with two instruments, each of which contributes its own background. Statistics enables the extraction of the DUT noise spectrum, even if it is significantly lower
than the instrument background, and even below the shot noise and thermal noise of the environment.
After physical insight on the theory, we analyze a few experimental techniques, with reference to phase noise and amplitude noise in RF/microwave systems and in photonic systems. Applications follow, in a surprisingly wide range of domains: radio-astronomy, radiometry, quantumoptics, thermometry (fundamental and applied),
semiconductor technology, metallurgy, etc.

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