Einstein-Podolsky-Rosen quantum entanglement for future gravitational-wave detectors

Quantum Noise limits the sensitivity of gravitational wave interferometers across the full detection band (10 Hz - 10 kHz). Current detectors mitigate quantum noise through frequency-dependent squeezing using large, detuned filter cavities. However, such infrastructure poses challenges for future detectors like the Einstein Telescope, which require more compact and cost-effective solutions. A promising alternative uses Einstein-Podolsky-Rosen (EPR) entanglement to achieve frequency-dependent squeezing without external filter cavities. We are developing an experiment in Virgo's R&D squeezing laboratory at the European Gravitational Observatory to investigate EPR-based frequency-dependent squeezing in the audio band. The project involves researchers from INFN groups and universities in Italy and institutions in South Korea. After a brief introduction to the scientific motivation, this work describes the main components and summarizes the current status of our experiment and its potential impact on third-generation gravitational wave detectors.