高Q谐振腔中针对非单色轴子信号的有效亚量子读出
Effective Sub-Quantum Readout for Non-Monochromatic Axion Signals in High-$Q$ Haloscopes
- The Oskar Klein Centre, Department of Physics, Stockholm University（斯德哥尔摩大学）
- Department of Physics, Yale University（耶鲁大学）
- Wright Laboratory, Yale University（耶鲁大学赖特实验室）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
该研究针对高Q谐振腔中非单色轴子信号，通过约瑟夫森参量放大器将共振调至半泵浦频率，使信号对称分布于信号带与闲置带，实现标准量子极限减半，提升了暗物质搜寻的灵敏度。
AI中文摘要：
利用微波谐振腔谐振腔搜寻波状暗物质的工作受限于标准量子极限，该极限规定，对于窄带信号，保相线性放大会导致系统总噪声至少为一个量子。我们证明，对于耦合至高Q谐振腔的非单色轴子信号，该极限可有效减半。通过将约瑟夫森参量放大器的谐振腔共振精确调至半泵浦频率，轴子信号会对称地分布在信号带和闲置带中。通过对零差读出进行正交分析，我们表明，这些镜像频谱分量的非相干求和使测量到的信号功率翻倍，而真空噪声保持不变。该操作产生的有效噪声极限为每个频率 bin 0.5 个量子，经最优匹配滤波后，整体有效极限为 $1/\sqrt{2}$ 个量子。
英文摘要：
The search for wave-like dark matter using microwave cavity haloscopes is constrained by the Standard Quantum Limit, which dictates that phase-preserving linear amplification results in a minimum of one quantum of total system noise for a narrow-band signal. We demonstrate that this limit is effectively halved for a non-monochromatic axion signal coupled to a high-$Q$ cavity. By operating a Josephson Parametric Amplifier such that the cavity resonance is centered exactly at the half-pump frequency, the axion signal symmetrically populates both the signal and idler bands. Through quadrature analysis of the homodyne readout, we show that the incoherent sum of these mirrored spectral components doubles the measured signal power while the vacuum noise remains constant. This operation yields an effective noise limit of 0.5 quanta per frequency bin, translating to an overall effective limit of $1/\sqrt{2}$ quanta after optimal matched filtering.
