Einstein–Podolsky–Rosen conditional squeezing for next generation gravitational-wave detectors

Frequency-dependent squeezing (FDS) represents a well established way to address quantum noise (QN) in Gravitational-Wave (GW) Earth-based detectors, such as LIGO, Virgo, and KAGRA. This technique is realized with the use of an external detuned optical resonator, the filter cavity. The experiment we present here is a table-top prototype that will probe a cheaper, more compact and more flexible strategy for broadband QN reduction (Ma et al., 2017). This scheme is based on two-mode Einstein–Podolsky–Rosen (EPR) entangled squeezed light, and it works without any filter cavity. The EPR-entangled beams will propagate in a small-scale suspended interferometer with high-finesse arm-cavities. This experiment aims at validating the EPR conditional squeezing at audio frequencies, suited for GW detection, implementing also innovative optical techniques.