Nondegenerate internal squeezing: An all-optical, loss-resistant quantum technique for gravitational-wave detection

The detection of kilohertz-band gravitational waves promises discoveries in astrophysics, exotic matter, and cosmology. To improve the kilohertz quantum noise-limited sensitivity interferometric gravitational-wave detectors, we investigate nondegenerate internal squeezing: optical parametric oscillation inside signal-recycling cavity with distinct signal-mode idler-mode frequencies. We use an analytic Hamiltonian model to show that this stable, all-optical technique is tolerant decoherence from loss it, its optimal readout scheme, feasible for broadband enhancement.