Interference-induced three-beam quantum squeezing enhancement

Quantum squeezed states, exhibiting noise reduction below the shot-noise limit, are important resources in quantum optics. The degree of quantum squeezing directly influences the performance of physical systems, making the achievement of higher squeezing levels essential. Here, by utilizing the phase-sensitive cascaded four-wave mixing (PSCFWM) processes, we experimentally demonstrate the enhancement of three-beam quantum squeezing. The intensity-difference squeezing among the three output beams from PSCFWM processes is about 8.2 dB, which is enhanced by about 1.3 dB compared with that generated by phase-insensitive cascaded four-wave mixing processes. Our scheme provides an effective way for enhancing multi-beam quantum squeezing and holds promise for applications in multimode quantum correlated imaging and multiparameter quantum precision measurement.