发表机构
University College London; National Physical Laboratory（伦敦大学学院; 英国国家物理实验室）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究制备嵌入Nb纳米桥DC SQUID的Nb基CPW谐振器，通过双音光谱法研究其非线性行为，实现15 dB参量放大，验证了克尔非线性振荡器模型并提出设计改进方向。
AI 中文摘要
超导电路在量子计算和量子传感的发展中发挥着至关重要的作用。这类电路通常需要包含一个非线性元件，其中工程化的非谐性（克尔因子）和谐振线宽决定了电路的潜在应用。在本研究中，我们制备了基于Nb的共面波导（CPW）谐振器，该谐振器嵌入了以Nb纳米桥作为弱连接的直流超导量子干涉器件（DC SQUID）。我们采用双音光谱法在15 mK的温度下、最高2.48 mT的磁场中研究该器件的非线性行为。在施加蓝失谐泵浦时，器件的谐振频率会降低，这一特性被用于估算克尔因子。我们进一步施加红失谐泵浦，使其超出分岔阈值，观察到额外闲频模式的出现，该模式具有净增益。通过进一步降低泵浦频率，器件的增益达到最大化，实现了15 dB的最大放大。最后，我们证明了克尔非线性振荡器模型与测量的传输光谱之间的一致性，并强调了可用于提升此类器件增益和带宽的进一步设计修改方案。
英文摘要
Superconducting circuits play a crucial role in the advancement of quantum computing and quantum sensing. Typically such circuits require the presence of a non-linear element, where the engineered anharmonicity (Kerr factor) and resonant linewidth determine the potential applications of the circuit. In this work we have fabricated Nb-based CPW resonators embedded with a DC SQUID incorporating Nb nanobridges as the weak links. We use two-tone spectroscopy to study the non-linear behaviour of the device at 15 mK up to a field of 2.48 mT. Under the application of a blue-detuned pump, the device shows a decrease in the resonant frequency which is used to estimate the Kerr factor. We further apply a red-detuned pump to go beyond the bifurcation threshold and observe the appearance of an additional idler mode with net gain. The gain of the device was maximized by further decreasing the pump frequency, showing a maximum amplification of 15 dB. Finally, we show agreement between the Kerr non-linear oscillator model and the measured transmission spectrum, and highlight further design modifications to improve the gain and bandwidth of such devices.
