AI 中文总结
研究利用直流SQUID及读出链对高Q值超导LC谐振器进行读出，发现Q值和有效温度与SQUID磁通偏置点有关，可据此推断相关参数，为基于集总元件谐振器及SQUID读出的实验提供原型，尤其用于低质量轴子搜索。
AI 中文摘要
我们展示了使用直流SQUID和SQUID串联阵列放大器读出链，对在约250kHz时Q值约为2×10⁶的超导LC谐振器进行读出。发现Q值取决于SQUID磁通偏置点，在SQUID调制曲线浅斜率点附近增加，在陡斜率点附近减小，与先前观察到的SQUID阻尼效应一致。由此推断SQUID有效输入阻抗，还从噪声谱中的共振峰推断谐振器电路的有效温度，且其也取决于SQUID磁通偏置点，表明可能存在SQUID反作用噪声贡献。该系统为未来基于带有SQUID读出的集总元件谐振器的实验提供了工作原型，特别是在DMRadio计划内的低质量轴子搜索。
英文摘要
We demonstrate the readout of a superconducting $LC$ resonator, with $Q \approx 2 \times 10^{6}$ at approximately 250 kHz, using a dc SQUID followed by a SQUID series-array amplifier readout chain. We find that $Q$ depends on the SQUID flux-bias point, increasing near the shallow-slope point of the SQUID modulation curve and decreasing near the steep-slope point, consistent with the previously observed SQUID damping effects. From this variation, we infer the SQUID effective input impedance. We further infer the effective temperature of the resonator circuit from the resonance peak in the noise spectrum and show that it also depends on the SQUID flux-bias point, suggesting a possible contribution from SQUID back-action noise. This system provides a working prototype for future experiments based on lumped-element resonators with SQUID readout, in particular low-mass axion searches within the DMRadio program.
Comments10 pages, 6 figures, 1 table
