Experimental demonstration of a classical analog to quantum noise cancellation for use in gravitational wave detection

The squeezed light which was used to breach standard quantum limits (SQL) was investigated using classical analog of quantum noise reduction. SQL was breached in an interferometer by the use of squeezing to correlate orthogonal quadratures of quantum noise. The Michelson interferometer was used to generate requisite amplitude modulation while frequency modulation was obtained by stressing laser crystal with piezoelectric transducer (PZT). The classical and correlated noise was imprinted on laser beam incident on Fabry-Perot cavity. The excess classical noise was cancelled by couplings between quadratures due to movable mirror which was sensitive to radiation pressure.