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中国物理学会期刊

压缩增强的强度噪声抑制机理

CSTR: 32037.14.aps.74.20241674

Mechanism of suppressing noise intensity of squeezed state enhancement

CSTR: 32037.14.aps.74.20241674
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  • 激光光源的噪声直接影响精密测量系统的精度和灵敏度, 特别是在引力波探测和生物成像等高精度应用中. 尽管经典反馈控制技术能有效地抑制强度噪声, 但其降噪水平受到经典噪声极限的限制. 本研究提出一种结合量子压缩光与经典反馈控制技术的新方法, 旨在进一步降低系统中的强度噪声, 突破经典反馈控制技术的抑噪瓶颈. 通过引入正交振幅压缩态光场, 在理论上建立了压缩光辅助的反馈控制系统, 理论分析了反馈增益和压缩度对噪声抑制的影响, 并与经典方案进行对比. 理论分析结果表明, 压缩光的引入显著地提高了噪声抑制水平, 接近散粒噪声极限, 从而大幅提升系统的灵敏度. 该方法为在不增加激光功率的情况下实现更低噪声水平提供了新的量子控制手段, 对精密测量技术的发展具有重要意义.

     

    This research focuses on advanced noise suppression technologies for high-precision measurement systems, particularly addressing the limitations of classical noise reducing approaches. The noise level of laser sources is a crucial factor that directly affects the measurement sensitivity in applications such as gravitational wave detection and biomedical imaging. Classical feedback control technologies are effective but often encounter a bottleneck resulting from the classical noise suppression limits. To cope with these challenges, a novel method integrating quantum squeezed light with classical feedback control systems to reduce intensity noise is proposed in this work. By employing an amplitude-squeezed light field, a quantum-enhanced feedback control model is developed, thereby theoretically examining the influence of both the feedback loop gain and the degree of squeezing on the noise suppression performance. The results show that the injection of squeezed light significantly reduces the intensity noise, approaching the shot noise limit (SNL), thereby improving the system sensitivity beyond the classical noise reduction boundaries. Specifically, –10 dB squeezed state injection into the feedback system yields an additional noise suppression of approximately 8.97 dB, exceeding what is achievable using classical feedback alone. This demonstrates that the potential of the proposed method can enhance measurement precision close to the quantum noise limits without increasing the laser power. The analysis highlights the asymmetric noise suppression effects between the inner feedback loop and outer feedback loop. Although the outer loop benefits significantly from the squeezed light injection and achieves noise levels that are unattainable by classical feedback methods, the inner loop shows relatively minor improvements. This asymmetry is attributed to the inherent characteristics of quantum squeezing and the limitations of the feedback loop design. Further investigation into the individual noise components reveals that the primary contributors to the intensity noise include input noise, photodetector noise, and beam splitter-induced vacuum fluctuations. The injection of squeezed light effectively mitigates these vacuum fluctuations, which are typically a major noise source in high-precision laser systems. Theoretical research results show that the use of squeezed light in feedback control systems can effectively enhance noise suppression, equivalent to a nine fold increase in detected optical power, without the physical drawbacks of increasing laser power such as thermal noise. In conclusion, this study provides a theoretical validation of combining quantum squeezed states with classical feedback control to exceed classical noise suppression limits. The integration of a –10 dB squeezed state demonstrates a significant noise reduction, showing that this hybrid approach could revolutionize noise management in precision measurement applications. The results pave the way for further exploring quantum-enhanced control technologies in fields such as gravitational wave detection, quantum communication, and advanced optical sensing, providing a pathway for improving sensitivity and noise suppression without increasing additional power requirements.

     

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