Squeezed Input Interferometer Laser GW Detector Faraday isolator The squeeze source drawn is a ponderomotive squeezer, but it could be any other squeeze source, e.g. an optical parametric oscillator, like the one shown in last slide. Squeeze Source Homodyne Detector GW Signal

Radiation-oscillator coupling  Amplitude-phase correlations 1. Light with amplitude fluctuations DA incident on mirror Movable mirror Field transformation: Incident laser light is in a coherent state (noise ball) Coupling to mirror motion Reflected light is in a squeezed state (noise ellipse) 2. Radiation pressure due to DA causes mirror to move by Dx 3. Phase of reflected light Df depends on mirror position and hence light amplitude, i.e DA  Dx  Df

Nonlinear optical medium b b a a Parametric oscillation Second harmonic generation The black cloud is a nonlinear material, e.g. LiNbO3. Operators a and b are creation and annihilation operators a  low energy photon (red, 1064 nm) b  high energy photon (green, 532 nm) First term in Hamiltonian gives optical parametric oscillation (OPO)  One high energy photon gives two (correlated) low energy photons Second term in Hamiltonian gives SHG  two low energy photons give on high energy photon Energy and momentum are conserved. a a The output photon quadratures are correlated a b a Parametric amplification

Optical Parametric Oscillator SHG