Generating long-term stable squeezed states via multiple pump noise suppression.

Pump power fluctuations are a critical factor in limiting the long-term stability of quantum sensing light sources. However, existing laser power stabilization techniques fail to efficiently address power fluctuations caused by downstream beam-pointing noise coupling. Here, we propose an optimized suppression scheme of pump power fluctuations that integrates a passive second harmonic process and active feedback control, achieving multiple noise suppression of both pointing and intensity noise in the pump field. Within the measurement time of 8.5 hours, we achieve a quantum sensing light source with a squeezing factor of 10.0 dB and its fluctuations below 0.4 dB. The proposed approach effectively boosts the long-term stability of the quantum squeezing source, thus paving a solid way for expanding the utilization of squeezing sources within the realm of quantum precision measurement.