Thermally controlled optical resonator for vacuum squeezed states separation

• Published in: Applied optics (2004) 2022-06, Vol.61 (17), p.5226
• Main Authors: Nguyen, C., Bréelle, E., Barsuglia, M., Capocasa, E., De Laurentis, M., Sequino, V., Sorrentino, F.
• Format: Article
• Language: English
• Subjects: Broadband; Compressing; Detectors; Entangled states; Etalons; Gravitational waves; Optical resonators; Quantum entanglement; Sensors; Squeezed states (quantum theory)
• ISSN: 1559-128X; 2155-3165
• DOI: 10.1364/AO.459190

Future gravitational-wave detectors will use frequency-dependent squeezed vacuum states to obtain broadband reduction of quantum noise. Quantum noise is one of the major limitations to the sensitivity of these detectors. Advanced LIGO+, Advanced Virgo+, and KAGRA plan to generate frequency-dependent squeezed states by coupling a frequency-independent squeezed light state with a filter cavity. An alternative technique is under consideration, based on conditional squeezing with quantum entanglement: Einstein–Podolsky–Rosen (EPR) squeezing. In the EPR scheme, two vacuum entangled states, the signal field at ω 0 and the idler field at ω 0 + Δ , must be spatially separated with an optical resonator and sent to two separate homodyne detectors. In this framework, we have designed and tested a solid Fabry–Perot etalon, to be used in an EPR table-top experiment prototype, thermally controlled without the use of a control probe optical beam. This device can also be used in optical experiments where the use of a bright beam to control an optical resonator is not possible, or where a simpler optical device is preferred.