Study and experiment on the alternative technique of frequency-dependent squeezing generation with EPR entanglement for Virgo

In this paper, we summarize the present state-of-the-art on the proof-of-principle experiment of frequency-dependent squeezing implemented through EPR entanglement for Virgo gravitational-wave detector and we introduce Virgo subsystem proposal for frequency-dependent squeezing, obtained with a compact apparatus and without the costs required by the infrastructure for the filter cavity.