论文标题
源自嵌入的库珀对晶体管的非线性电荷和可磁性腔
A Nonlinear Charge- and Flux-Tunable Cavity Derived from an Embedded Cooper Pair Transistor
论文作者
论文摘要
我们介绍了腔室的库珀对晶体管（CCPT），该设备的表现是高度非线性微波腔，可以通过为栅极电容器充电和通过鱿鱼环将磁通线螺纹来调节其谐振频率。我们表征了该设备，并在理论和实验之间找到了极好的一致性。这种表征的一个关键困难是频率波动的存在与腔线宽度可比性相当，这与最近的理论预测相符[Brock等，Phys。修订版应用14，054026（2020）]。通过在参数空间中精心选择的点上测量这些频率波动的功率频谱密度，我们发现它们主要是$ 1/f $电荷和通量噪声在固态设备中常见的结果。值得注意的是，我们还观察到通过KERR非线性在腔场中量子波动引起的频率波动的关键特征。
We introduce the cavity-embedded Cooper pair transistor (cCPT), a device which behaves as a highly nonlinear microwave cavity whose resonant frequency can be tuned both by charging a gate capacitor and by threading flux through a SQUID loop. We characterize this device and find excellent agreement between theory and experiment. A key difficulty in this characterization is the presence of frequency fluctuations comparable in scale to the cavity linewidth, which deform our measured resonance circles in accordance with recent theoretical predictions [Brock et al., Phys. Rev. Applied 14, 054026 (2020)]. By measuring the power spectral density of these frequency fluctuations at carefully chosen points in parameter space, we find that they are primarily a result of the $1/f$ charge and flux noise common in solid state devices. Notably, we also observe key signatures of frequency fluctuations induced by quantum fluctuations in the cavity field via the Kerr nonlinearity.
